c. 


UNIVERSITY  OF  CALIFORNIA. 


FROM  THE    LIBRARY  OF 

DR.  JOSEPH   LECONTE. 

GIFT  OF  MRS.   LECONTE. 
No. 


/ r      <J> 


OUTLINES 


OP 


A    SYSTEM 


OP 


MECHANICAL   PHILOSOPHY 


BEING   A 


RESEARCH    INTO    THE    LAWS    OF   FORCE. 


SAMUEL   ELLIOTT  COUES. 


"  That  which  we  call  gravitation  and  fancy  ultimate,  is  but  one  fork  of  a  mightier 
stream  for  which,  as  yet,  we  have  no  name." 


BOSTON: 

CHARLES  C.  LITTLE  AND  JAMES  BROWN. 
1851. 


Entered  according  to  Act  of  Congress,  in  the  year  1851,  by  CHARLES  C. 
LITTLE  AND  JAMES  BROWN,  in  the  Clerk's  Office  of  the  District  Court  of  the 
District  of  Massachusetts. 


CAMBRIDGE: 

PRINTED   BY   BOLLES   AND   HOUGHTON. 


TO     THE 

REV.  ANDREW  P.  PEABODY. 

MY    DEAR    SIR! 

When  I  first  mentioned  that  I  had  undertaken  a  Research 
into  the  Laws  of  Force,  you  encouraged  me  to  follow  up  the 
investigation ;  and  from  that  time  you  have  constantly  extended 
to  me  your  sympathy,  and  have  manifested  a  kind  interest  in 
the  result  of  my  labors.  Thus  you  are  intimately  associated 
in  my  mind  with  the  work,  though  it  is  but  just  to  say  that  you 
are  in  no  sense  responsible  for  the  correctness  of  any  of  my 
deductions.  I  dedicate  the  book  to  you  as  an  acknowledgment 
of  your  kindness,  and  as  a  manifestation  of  my  respect  for 
the  power  of  mind  which  has  not  only  given  you  your  eminent 
position  in  your  profession,  but  is  conspicuous  in  every  depart- 
ment of  learning  to  which  your  attention  has  been  directed. 
With  sincere  regard, 

Your  friend, 

SAMUEL  E.  COUES. 


ERRATA. 

Page  107,  line  30th  —  read,  descends  to  a  lower  level. 
"     163,  line  8th  —  for  bury,  read  buoy. 
11    258,  line  4th  — for  their,  read  these. 
"    263,  line  2d  —  for  common,  read  coming. 
u    272,  note  —  omit  the  quotation  marks  in  the  second  paragraph. 
"    280,  line  5th  —  insert  the  before  work  —  next  line,  omit  the  before  law. 


CONTENTS 


INTRODUCTION. 


CHAPTER  I. 
GENERAL  PROPOSITIONS  RELATING  TO  FORCE  AND  MOTION.       .      4 

CHAPTER  II. 

PLANETARY  MOVEMENTS.  FORCE  FROM  THE  FALL  or  BODIES.  HEAT. 
LIGHT.  ELECTRICITY.  GALVANISM.  MAGNETISM.  ANIMAL  FORCE. 
IDENTITY  OF  FORCE.  .  .  .  •  .-  .  ' 17 

CHAPTER  III. 

CAPILLARY  ATTRACTION.  ELASTICITY.  COHESION.  FRICTION. 
SEPARATION  OF  COHESION.  CEMENTS.  CHEMICAL  AFFINITY.  44 

CHAPTER  IV. 

ACTION  AND  REACTION.  REACTION  AS  A  PROPELLING  POWER. 
Yis  INERTIA,  MECHANICAL  POWERS.  CENTRIFUGAL  FORCE.  60 

CHAPTER  V. 

OSCILLATION.  MOVEMENT  OF  THE  WAVES.  WHIRLPOOLS  AND 
WHIRLWINDS.  VORTICAL  MOVEMENT.  OSCILLATION  OF  THE 
SURFACE  OF  THE  EARTH.  GEOLOGICAL  EPOCH.  FORCE  OF  DE- 
SCENT. .  85 


VI  CONTENTS. 


CHAPTER  VI. 

ATMOSPHERIC  DENSITY.  GRAVITATION  OP  THE  ATMOSPHERE. 
ELASTICITY  OF  AIR.  ACTION  OF  THE  BAROMETER.  THE  BAR- 
OMETER THE  DIRECT  MEASURE  OF  ALTITUDE.  .  .  .113 

CHAPTER   VII. 
PRESSURE  OF  FLUIDS.         .        . 151 

CHAPTER  VIII. 

PRESSURE  OF  ELUIDS,  CONTINUED.  GRAVITATION  OF  FLUIDS.  CO- 
NICAL ADJUTAGES.  RELATIVE  LEVELS  OF  AIR  AND  WATER. 

178 

CHAPTER  IX. 
THE  TIDES.  .        ,.     ^       ^." 225 

CHAPTER  X. 

TRADE  WINDS.  OCEANIC  CURRENTS.  ERRATIC  DRIFT.  METEOR- 
OLOGY. .  .  .  .  .  .  .  ...  253 

CHAPTER  XL 
THE  MATHEMATICAL  ARGUMENT  FOR  GRAVITATION.       .        .        284 

CHAPTER   XII. 

LAW  OF  THE  VELOCITY  OF  FALLING  BODIES.  ORIGIN  OF  THE  THE- 
ORY OF  GRAVITATION.  MOVEMENTS  OF  THE  SPHERES.  HARMONY 
OF  SCIENCE  WITH  REVELATION.  .  .  .  .'•'»•  308 


INTRODUCTION. 


THESE  outlines  of  a  System  of  Mechanical  Philosophy 
are  the  result  of  a  research  made  by  the  author,  for  his  own 
instruction.  In  the  research  he  attempted  to  separate  sup- 
position from  fact,  —  the  questionable  from  those  things 
necessarily  taken  for  truth  by  the  laws  of  the  mind.  The 
inquiry  took  the  form  of  snythetical  reasoning,  proceeding 
step  by  step,  deducing  the  unknown  from  what  appeared 
self-evident,  taking  nothing  as  truth  on  authority,  however 
great  the  name  which  had  given  currency  to  the  theory ; 
thus  shutting  out  all  sources  of  error  except  such  as  resulted 
from  the  weakness  of  the  individual  mind.  Arriving  by 
this  process  at  conclusions,  the  very  opposite  of  those  taught 
in  the  schools  of  science,  these  conclusions  were  tested  by 
an  appeal  to  the  phenomena  of  nature.  Both,  the  reasoning 
without  the  phenomena,  and  the  phenomena  without  the 
reasoning,  pointed  to  the  same  general  truths. 

Thus  are  presented  opinions  which  appear  to  be  sup- 
ported both  by  reason  and  by  observation,  and  presented 
in  the  order  of  their  development.  The  writer  feels  con- 
fident, that,  however  defective  may  be  his  logic,  however 
imperfect  may  be  his  statement  of  the  facts  of  science, 
however  crude  may  be  his  application  of  the  truth  to  the 
i 


2  INTRODUCTION. 

explanation  of  phenomena,  he  has  unfolded  some  principles, 
which,  when  distinctly  evolved  from  mingled  error,  will 
change  somewhat  the  basis  on  which  mechanical  philosophy 
now  rests. 

But,  whether  or  not  the  opinions  here  presented  are 
demonstrated  to  the  minds  of  scientific  men,  it  is  admitted 
that  many  of  the  present  explanations  of  philosophy  are 
received  as  the  supposed  best  possible  explanations,  rather 
than  as  settled  truth,  on  which  the  mind  confidently  reposes. 
The  conservatives  in  science  may  be  successful  in  pointing 
out  the  errors  of  new  theories,  but  they  have  other  more 
difficult  work,  that  of  the  defence  of  the  old  theories. 

A  reexamination  of  principles  supposed  to  be  forever  set- 
tled by  the  authority  of  a  Newton  may  strike  many  minds 
as  presumptuous.  It  will  be  seen,  however,  that  the  splen- 
did conceptions  of  Kepler,  made  distinct  and  thoroughly 
demonstrated  by  Newton,  are  not  assailed.  The  glorious 
truth  of  the  harmony  of  the  movements  of  the  spheres,  by 
which  the  astronomer  can  track  out  the  orbit  of  the  most 
eccentric  wanderer  of  the  heavens,  stands  forever,  the  reflex 
of  the  light  of  creation  from  the  minds  of  the  truly  great. 

It  is  the  school  which  now  determines  opinions  on  philo- 
sophical subjects.  Men  are  taught  to  believe  rather  than  to 
reflect,  —  to  receive  opinions  rather  than  to  evolve  them  by 
the  process  of  intense  thought.  A  scientific  education  is  a 
capital,  the  value  of  which  is  impaired  by  dissent.  It  would 
seem  as  if  nothing  further  could  be  attained,  as  if  philosophy 
had  soared  its  highest  flight ;  for  theories  thus  pass  from 
mind  to  mind,  from  generation  to  generation,  as  settled 
truths,  and  theories  too,  somewhat  questioned  or  indistinctly 
comprehended,  even  by  those  who  teach  them. 

To  induce  reflection,  therefore,  upon  admitted  theories, 


INTRODUCTION.  3 

cannot  fail  to  do  some  service  to  the  cause  of  truth  ;  for,  as 
it  has  been  observed,  "  nothing  tends  more  to  the  corrup- 
tion of  science  than  to  suffer  it  to  stagnate.  The  waters 
must  be  troubled  before  they  can  exert  their  healing  virtues. 
A  man  who  works  beyond  the  surface  of  things,  though  he 
may  be  wrong  himself,  yet  clears  the  way  for  others,  and 
may  chance  to  make  his  errors  subservient  to  the  cause  of 
truth." 

This  work  is  not  intended  as  an  elaborate  philosophical 
treatise,  but  as  a  rapid  outline ;  and  only  those  consider- 
ations are  presented  which  are  necessary  to  develop  the 
opinions  advanced.  Much  collected  material  has  been 
laid  aside  for  future  use,  if  it  be  thought  that  the  opinions 
set  forth  are  worthy  of  additional  attention. 

PORTSMOUTH,  N.H.,  Sept.  7,  1850. 


CHAPTER  I. 


"  FOR  SINCE  THE  HUMAN  MIND  PARTICIPATES  AS  IT  MAY  IN  THE 
FRUITFULNESS  OF  THE  CREATIVE  NATURE,  IT  DOTH  FOR  ITSELF 
BRING  FORTH  REASONABLE  THOUGHTS." 

IN  all  investigations  of  matter  and  force,  we  must  divest 
them  of  all  properties  that  are  boundless,  that  are  without 
fixed  limits,  determinate  degrees.  Thus,  matter  is  not  infi- 
nite in  its  extent  nor  in  its  capacity  for  motion  ;  so  of  force, 
its  action  is  not  infinite  ;  it  has  parts,  or  divisions,  each 
with  a  fixed  rate  of  power,  and  as  a  whole,  its  aggregate 
power  is  fixed, — meted  out  by  Him  by  whose  infinite  power 
it  was  constituted.  We  need  recurrence  to  this  as  the 
point  of  departure  in  our  course,  as  that  to  which  we  can 
recur  as  something  fixed,  when  the  ocean  on  which  we 
speed  our  way  has  no  guide  for  our  path  over  its  vastness. 
There  is  one  God,  the  ultimate  Cause  of  all  things,  of  whom 
alone  can  infinity  of  attributes  be  affirmed.  This  truth  is 
here  presented,  not  for  its  religious  bearing,  but  from  the 
necessity  of  recurring  to  it  in  its  relations  to  the  first  prin- 
ciples of  philosophy.  The  admission  that  His  attributes 
alone  are  infinite  in  degree,  is  essential  to  distinctness  of 
opinion  with  regard  to  matter  and  force.  The  human  mind 
cannot  comprehend  infinity;  any  proposition,  therefore, 
which  involves  the  boundless,  is  unintelligible ;  decide  it 
affirmatively  or  negatively,  the  mind  feels  no  confidence  in 
the  result. 


OUTLINES,   ETC.  5 

1.  Matter  has  inertness  as  an  essential  property  ;  it  has 
substance  and  extension  ;  it  exists  in  atoms  or  ultimate  par- 
ticles, indestructible  and  impenetrable,  between  which  atoms 
there  is  space ;  these  atoms  aggregated,  constitute  masses, 
between   which   there  is  space  ;    these   masses  constitute 
worlds,  between  which  there  is  space.     Space  is  room  or 
freedom  for  motion,  or  that  in  which  matter  exists  and  is 
moved.     Motion  is  the  act  of  the  change  of  place  of  mat- 
ter ;   it  is  the  passing  of  matter  from  one  part  of  space  to 
another.    No  atom  of  matter  can  occupy  the  same  place  with 
another  atom.     Force  is  that  which  produces  the  motion  of 
matter,  or  that  which  causes  matter  to  act.     Force  cannot 
act  where  it  is  not. 

These  definitions  are  the  usual,  commonly  received  defini- 
tions of  matter  and  force,  and  the  resultant  motion.  We 
express  in  them  all  that  can  be  known.  An  inquiry  into 
their  nature  or  construction  embraces  the  element  of  the 
infinity  of  God  who  created  them,  and  "  plunges  us  at  once 
into  that  deep  which  never  yet  was  fathomed  by  human 
intellect."  Newton  thus  speaks  of  matter.  "  We  believe 
that  God  in  the  beginning  formed  matter  in  solid,  hard, 
massy,  impenetrable,  movable  particles,  of  such  sizes,  fig- 
ures, and  other  properties,  and  in  such  proportion  to  space, 
as  most  conduced  to  the  end  for  which  He  formed  them  ; 
and  that  these  primitive  particles  being  solids,  are  incom- 
parably harder  than  any  porous  bodies  compounded  of  them, 
even  so  very  hard  as  never  to  wear  or  to  break  to  pieces  ; 
no  ordinary  power  being  able  to  divide  what  God  himself 
made  one  at  the  first  creation." 

2.  That  which  is  moved  and  that  which  moves  it,  are  not 
identical, — not  the  same  thing  ;  the  one,  matter,  having  in- 


6  OUTLINES   OF   A   SYSTEM   OF 

ertness  as  an  essential  property ;  the  other,  force,  having 
as  an  essential  property  power  to  give  motion.  Wherever 
matter  is,  there  is  inertness ;  wherever  force  is,  there  is 
motion. 

The  belief  of  the  separate  and  independent  existence  of 
cause  and  effect  results  from  the  constitution  of  the  mind. 
It  is  what  God  compels  us  to  believe.  It  is  as  inspiration. 
We  think  of  God  as  existing  separate  from  his  creation, 
of  our  minds  as  separate  from  thought  and  perception ;  and 
so  of  force,  as  an  independent  power,  as  in  no  sense  matter, 
but  as  that  which  gives  motion  to  matter,  as  that  which 
causes  matter  to  change  its  place.  This  separate  existence 
is  recognized  in  the  three  great  laws  of  motion,  which  refer 
to  force  as  the  cause  of  motion. 

These  words  of  Herschell  very  distinctly  present  the 
idea :  "  Force  may  be  communicated  to  inanimate  matter, 
it  may  be  concentrated  in  the  same  mass  by  continuation  of 
animal  or  muscular  force.  We  thus  learn  to  regard  motion 
in  matter  as  the  effect  and  indication  of  force,  and  force 
may  be  defined  as  that  which  is  capable  of  producing  motion 
in  matter,  or  of  stopping  and  altering  its  direction  when 
produced."  Daniell  (Introduction  to  Chemical  Philosophy) 
says,  "  A  body  at  rest  would  remain  quiescent  unless  it  were 
to  receive  an  impulse  from  without,"  or  objectively,  and  thus 
philosophy  recognizes  the  inertness  of  matter.  Growing 
from  this  idea  is  the  doctrine  of  vis  inertise.  It  is  a  term 
expressive  only  of  the  fact,  that  matter  rests  when  unmoved, 
and  moves  when  not  at  rest,  and  that  time  often  elapses 
after  the  impulse,  before  motion  is  apparent.  Strictly  it 
asserts  the  impossibility  of  self-moving  matter. 

3.  Matter  which  is  in  motion  must  continue  in  a  state  of 


MECHANICAL    PHILOSOPHY.  7 

uniform  motion  forever,  unless  disturbed  by  the  action  of  an 
external  cause. 

The  same  cause  produces  the  same  effects.  This  propo- 
sition, so  far  as  it  goes,  is  identical  with  the  first  of  the  three 
great  laws  of  motion,  which  is,  "  A  body  must  continue  for- 
ever in  a  state  of  rest  or  of  uniform  motion,  in  a  straight 
line,  if  not  disturbed  by  the  action  of  an  external  cause." 
If  this  be  true  of  bodies  both  at  rest  and  in  motion,  the  pro- 
position is  true  as  regards  bodies  in  motion,  and  as  true  when 
considered  apart  from  the  direction  of  the  motion  as  it  is 
when  the  law  defines  the  line  of  motion. 

4.  All  motion  is  in  proportion  to  the  force  which  pro- 
duces it. 

The  degree  of  the  effect  is  in  proportion  to  the  cause  ; 
in  other  words,  add  to  or  take  from  the  force  in  action  upon 
given  matter,  the  quantity  of  motion  is  changed  propor- 
tionally. The  second  of  the  three  laws  is  :  "  Every  change 
of  motion  produced  by  the  external  (objective)  cause  is 
proportional  to  the  force  impressed,  and  in  the  direction  of  a 
straight  line  in  which  the  force  acts."  The  proposition 
affirms  the  first  clause  of  the  law,  and  this  is  necessarily 
true  independently  of  the  truth  of  the  latter  clause. 

We  draw  from  this  proposition  the  following  as  corrolla- 
ries :  1st,  that  force  is  divisible,  different  quantities  or  degrees 
of  it  acting  at  different  times  on  the  same  matter ;  2d,  force 
is  transferable,  for  otherwise,  that  is,  without  transfer  of 
force,  there  could  be  no  increase  or  diminution  of  motion. 

5.  The  absolute  condition  of  the  transfer  of  force  is  its 
presence  with  matter  not  susceptible  of  motion  by  it. 

The  essential  property  of  force  being  action,  wherever  it 


8  OUTLINES   OF  A   SYSTEM   OF 

is,  it  acts,  or  from  its  nature  it  is  transferred  from  matter 
which  cannot  be  moved  to  matter  having-  space  for  motion. 

6.  The  degree  or  velocity  of  the  motion  of  a  mass  de- 
pends on  the  degree  of  force  which  acts  upon  each  atom 
constituting  the  moving  mass.     It  appears  self-evident,  that 
every  atom,  perhaps  in  a  degree  according  to  its  element  or 
kind,  requires  always  the  same  force  to  move  it  with  the 
same  velocity,  and  the  motion  of  the  mass  depends  on  the 
degree  of  force  relative  to  the  number  of  its  atoms. 

7.  Every  atom  of  the  solar  system  is  in  continued  motion, 
orbital  and  rotary. 

Hence  it  follows,  that  it  is  force  which  determines  the 
position  of  every  atom,  mass,  and  world,  and  determines 
their  position  positively  in  space.  It  also  determines  the 
relative  position  of  all  things. 

8.  Matter  occupies  but  one  place  in  space  at  the  same 
time,  and  consequently  no  atom  can  have  motion  but  in  one 
line  of  direction  at  the  same  time. 

Hence  it  follows,  that  all  motion  is  orbital,  rotary, 
-curvilinear ;  for,  all  atoms  being  in  curvilinear  motion,  no 
addition  of  rectilinear  motion  can  change  the  curve  into  the 
straight  line,  —  there  will  ever  remain  the  element  of  the 
curve.  The  contrary  opinion  indicates  infinity,  and  is  un- 
intelligible. The  foundation  principle  of  geometry  is  the 
measure  of  all  angles  by  arcs  of  the  circle,  and  the  meas- 
urement of  the  circle  or  curve  conversely  by  the  inscribed 
straight  lines  or  angles. 

Hence  the  fixed  relation  between  the  diameter  of  the 
circle  and  its  circumference,  and  the  measure  of  motion  by 


MECHANICAL   PHILOSOPHY.  9 

the  diameter  of  the  circular  orbit.  We  assume  that  the 
harmonic  motion  of  the  heavenly  bodies  bears  a  certain  pro- 
portion to  the  orbit,  that  this  velocity  has  a  fixed  ratio  to 
the  diameter,  and  that  this  ratio  mathematically  determined 
is  proportional  to  the  square  of  the  distance  of  the  circum- 
ference from  the  centre. 

The  velocity  of  bodies  moving  in  free  space  being  in  a 
fixed  ratio  to  the  orbit,  it  is  the  present  force,  the*  active 
principle,  which  determines  the  orbit.  A  change  of  the 
degree  of  force  would  enlarge  or  diminish  the  orbit.  In 
all  free  motion,  therefore,  the  motion  is  uniform  and  har- 
monic. Two  atoms  moving  in  the  same  orbit  will  move  with 
the  same  velocity ;  in  different  orbits  will  preserve  that  rela- 
tive position  which  is  determined  by  the  difference  of  orbit, 
and  the  difference  of  the  line  of  direction  ;  so  that  mathe- 
matically the  relative  position  of  any  body  can  be  deduced, 
given  as  the  elements  of  calculation  its  orbit  and  direction 
of  motion. 

9.  Rectilinear  motion,  or  motion  in  a  straight  line,  cannot 
be  affirmed  of  any  atom  belonging  to  or  in  harmony  with 
the  solar  system,  or  with  the  system  of  worlds.     The  hori- 
zontal line  on  the  surface  of  the  globe  is  curvilinear.     So 
from  any  one  point  to  another,  in,  on,  and  about  the  earth, 
the  moving  body  takes  the  curved  line.     In  the  old  philo- 
sophy, circular  motion  was  deemed  the  natural  motion ;  but 
the  new  philosophy  conceives  of  circular  motion  as  con- 
strained by  the  operation  of  conflicting  forces. 

10.  The  supposed  perpendicular  descent  of  a  falling  body 
is  a  curvilinear  motion.     This  is  not  practically  admitted, 
but  mathematically  deduced  ;  the  fall  is  termed  a  "  cubical 


10  OUTLINES    OF   A    SYSTEM    OF 

parabola."  The  supposed  attraction  of  the  earth  does  not 
draw  in  straight  lines,  falling  bodies  preserving  ever  their 
rotary  motion. 

11.  Bodies  in  rotation  with  the  earth,  on  receiving  addi- 
tional  force,  must  either  take  a  higher   level  of  rotation, 
or  use  the  force  received  in  additional   motion  in  a  new 
direction. 

12.  In  the  act  of  falling  whereby  a  lower  level  of  rota- 
tion is  assumed,  force  must  be  transferred  from  the  falling 
body  when  its  motion  is  suspended. 

The  motion  of  falling  is  added  to  the  rotary  motion, 
thereby  giving  action  to  the  present  force.  This  motion 
being  suspended,  only  rotary  motion  in  a  smaller  orbit 
remaining,  force  will  be  transferred.  Hence  arises  spare 
force  of  descent.  The  spare  force  of  descent  will  be  mea- 
sured by  the  degree  of  descent.  Hence  the  spare  force  of 
falling  bodies  is  measured  by  the  square  of  the  time  of 
descent,  equal  times  giving  equal  distances  of  descent. 
Thus  most  distinctly  is  presented  the  law  of  falling  bodies, 
or  motion  begetting  motion,  which,  indistinctly  understood, 
caused  the  great  controversy  between  the  schools  of  Des 
Cartes  and  Leibnitz,  and  which  to  this  day  has  obscured 
mechanical  science,  by  making  the  occasional  abnormal 
motion  of  falling  bodies  the  element  of  calculation  of  har- 
monic motion. 

13.  The  motion  of  the  heavenly  bodies  being  harmonic 
with  fixed  velocity  according  to  orbit,  their  velocity  is  the 
immediate  measure  of  the  velocities  of  retarded  or  accele- 
rated motion ;  that  is,  the  abnormal  motion  is  detected  and 


MECHANICAL  PHILOSOPHY.  11 

measured  by  the  normal,  the  motion  of  bodies  in  confined 
space  being  determined  by  the  velocity  of  bodies  in  free 
space. 

Time  is  the  indirect  measure  of  velocity  ;  the  motion  of 
the  earth  which  measures  time,  the  direct  measure  of  velo- 
city. Hence  all  velocity  is  known  by  and  measured  by  the 
rotation  of  the  earth.  A  body  which  moves  thirty  miles  in 
one  hour  moves  over  the  given  space  isochronously,  or 
while  the  earth  has  moved  one  twenty-fourth  part  of  her 
rotary  circle.  Time,  therefore,  has  no  reference  to  force 
and  motion  so  as  to  increase  or  diminish  them,  and  motion 
refers  to  time  only  as  indicating  the  extent  of  the  motion  of 
the  earth. 

14.  There  is  beside  the  consentaneous  motion  of  the 
atoms  of  the  mass,  or  the  progressive  motion  of  the  mass, 
an  atomic  or  molecular  motion  of  every  atom  composing  the 
mass. 

This  proposition  will  receive  its  most  perfect  demonstra- 
tion by  the  facts  and  phenomena  of  nature  ;  but  is  believed 
from  analogy,  that  the  same  law  governs  the  minute  as 
well  as  the  extended,  —  also  from  the  fact  that  there  is- 
space  between  all  atoms,  that  force  is  primarily  in  action  on 
the  atoms.  If  force  be  present  with  atoms,  and  there  be 
space  for  motion,  motion  is  affirmed.  We  leave  this  propo*- 
sition  mainly  upon  these  general  statements,  recurring,  ia 
this  place,  to  one  most  significant  fact :  "  The  expansion  of 
volume  of  small  bodies  by  dilatation  from  heat,  may  be  ob* 
tained  without  sensible  error  by  trebling  the  number  which 
expresses  its  increase  in  length."  Daniell's  Introduc- 
tion to  Chemical  Philosophy.  The  trebling  of  the  diameter, 
it  will  be  perceived,  gives  nearly  the  circumference  of  the* 
circle  of  motion. 


12  OUTLINES    OF   A    SYSTEM    OF 

15.  Force  transfers  itself  from  atom  to  atom  without  ap- 
preciable time.  Time  being  measured  by  the  action  of  force 
upon  a  given  quantity  of  matter,  the  transfer  of  force  with- 
out matter  is  therefore  without  time  ;  or  with  a  reduction 
of  the  matter,  velocity  is  increased  ;  annihilate  the  matter, 
and  time  is  no  longer  to  be  affirmed  of  its  passage.  Thus 
attraction  of  gravitation  is  spoken  of  "  as  a  force  which  is 
transmitted  instantaneously,"  and  so  of  light,  heat,  gal- 
vanism, &c.  So  far  as  they  pass  in  appreciable  time  it  is 
because  they  (the  forces  which  move)  are  connected  with  the 
material ;  the  essential  quality  of  pure  force  unembodied 

is  change  of  place  without  appreciable  time. 

' 

36.  Force  is  diffusible  only  by  contact  of  the  moving 
atom  with  another  atom.  This  appears  from  the  fact  that 
force  is  transferable  only  when  it  cannot  induce  motion,  and 
while  space  remains  there  is  room  for  motion.  Therefore, 
the  motion  of  a  body  must  be  after  a  lapse  of  appreciable 
time  from  the  contact  of  the  atoms.  Consentaneous  motion 
of  the  mass  is  from  the  equal  diffusion  of  motion  through  its 
particles.  These  particles  have  room  for  motion  before 
impingement ;  therefore,  the  mass  moves  in  appreciable 
time  from  the  contact  of  the  atoms. 

This  is  finely  illustrated  by  a  row  of  suspended  ivory 
balls  through  which  force  is  communicated  in  appreciable 
time  by  the  measured  motion  of  the  balls,  according  to  their 
distance  and  the  degree  of  force.  It  is  the  foundation  of 
the  doctrine  of  vis  inertiae.  It  is  not  impossible  that  the 
distance  of  atoms  constituting  a  mass  may  be  relatively 
determined  with  regard  to  the  distance  of  atoms  in  another 
mass.  It  will  be  found  that,  the  more  porous  the  body,  the 
longer  is  the  lapse  of  time  between  the  impingement  and  the 


MECHANICAL    PHILOSOPHY.  13 

motion  of  the  atoms  as  the  mass ;  we  instance  equal  weights 
of  atmospheric  air  and  of  lead.  The  force  is  communicated 
instantly,  motion  results  instantaneously,  but  time  is  predi- 
cable  of  the  passage  of  atom  to  atom,  to  diffuse  the  motion 
equally  that  it  may  be  consentaneous. 

17.  Force  acts  independently  of  direction  ;  on  its  trans- 
fer, its  former  line  of  motion  does  not  necessarily  imply  a  con- 
tinuance of  the  same  line  of  motion.  A  body  in  motion 
must  continue  forever  in  a  state  of  uniform  motion,  unless 
disturbed  by  the  action  of  an  objective  cause.  The  force 
will  be  transferred  upon  impact,  and  the  body  receiving  it 
will  move  in  the  direction  in  which  it  is  free  to  move  ;  or,  if 
the  body  which  obstructs  motion  be  not  movable,  the  force, 
not  being  transferred,  acts  in  the  opposite  direction. 

The  resultant  motion  of  impinging  bodies  is  demonstrated 
by  the  mathematical  figure,  the  "  polygon  of  force,"  and  is 
equally  demonstrable  by  the  diagram  showing  the  contact  of 
atoms  having  surface ;  so,  too,  the  angle  of  incidence  and 
reflection,  when  a  body  impinges  upon  an  immovable 
mass,  shows  that  the  resultant  motion  is  determined  only 
by  the  free  space  for  motion.  If  two  flat  surfaces  meet, 
they  can  be  separated  only  in  the  opposite  direction,  if  the 
separating  force  acts  equally  on  the  surface.  And  so 
through  more  complex  movements. 

We  refer  to  facts  of  common  observation ;  the  rotary 
motion  of  the  windmill  by  the  horizontal  impingement  of  the 
wind,  —  the  billiard  ball,  —  the  rise  of  the  wave.  On  this 
action  of  force,  independent  of  direction,  depends  the  appli- 
cation of  force  in  mechanical  combinations,  by  which  the 
force  of  falling  water  is  conveyed  anywhere,  and  acts  in  any 
direction.  Force  does  not  act  where  it  is  not ;  but  the  me- 

2 


14  OUTLINES   OF   A   SYSTEM   OF 

chanic,  availing  himself  of  the  laws  which  govern  its  trans- 
fer, leads  it  to  the  loom  and  opens  for  it  the  desired  line  of 
motion  only. 

This  doctrine  of  the  transfer  of  force  is  one  of  the  found- 
ations of  the  supposed  action  and  reaction  of  force  ;  every 
instance  of  reaction  can  be  directly  traced  to  the  transfer 
of  force. 

18.  Transfer  of  force,  which  does  not  give  the  body  to 
which  it  is  transferred  consentaneous  motion  of  its  atoms, 
gives  vibratory  motion  to  the  parts  of  the  mass,  or  increase 
of  molecular  motion,  the  motion  induced  being  of  the  same 
degree  as  the  motion  that  was  suspended.  The  force  being 
transferred,  and  motion  being  in  proportion  to  the  force,  the 
vibratory  or  molecular  motion  must  be  the  same  ;  or,  if  the 
motion  of  the  recipient  of  the  force  be  retarded,  an  equal 
quantity  of  its  force  is  also  turned  from  the  consentaneous 
motion,  so  that  the  resultant  motion,  internal  to  the  mass, 
will  be  doubled ;  that  is,  the  internal  motion  is  the  aggre- 
gate of  the  suspended  motion  of  both  impinging  masses. 
Thus,  the  motion  of  the  tongue  of  the  bell,  and  of  the  bell, 
jointly  increase  the  loudness  of  its  tone  ;  and  other  instances 
of  this  result  present  themselves  to  every  mind.  Hence  the 
concussion  and  destruction  of  two  balls  in  opposite  motion, 
which  would  not  result  from  the  motion  of  either  upon  the 
other  at  rest. 

Vibratory  motion  being  the  unequal  or  rather  unconsen- 
taneous  motion  of  the  parts  of  a  mass,  if  there  be  not  a 
gradual  increment  of  motion  from  the  surface  to  the  centre, 
there  will  be  nodes  or  points  of  rest.  Thus  musical  chords 
manifest  certain  points  of  rest. 

Vibratory  motion  being  determined  by  the  degree  of  force, 


MECHANICAL   PHILOSOPHY.  15 

if  the  same  quantity  of  matter  be  moved  the  same  distance, 
the  times  of  vibration  will  be  the  same  ;  if  the  distance  be 
diminished,  there  will  be  an  increase  of  velocity.  Tone  being 
dependent  on  time  of  vibration,  an  increase  or  diminution  of 
force  changes  the  range,  preserving  the  tone.  Isochronous 
vibration  is,  therefore,  a  branch  of  the  law  which  induces  the 
same  quantity  of  motion  by  the  same  quantity  of  force.  It 
follows,  too,  that  there  can  be  no  vibratory  or  reciprocal 
motion  in  free  space. 

19.  Force  is  indestructible.  This  appears  from  the  gen- 
eral consideration,  that  what  God  formed  at  the  beginning 
no  power  can  destroy.  It  is  imperishable,  too,  as  is  evident 
from  its  transfer  from  atom  to  atom  and  from  mass  to  mass, 
and  from  the  state  of  equable  motion,  which  bodies  actuated 
by  a  given  degree  retain.  It  is  also  one  and  identical. 
That  which  gives  motion  is  force  ;  if  it  have  different  essen- 
tial properties,  these  properties  cannot  be  detected,  as  force 
is  known  only  by  the  motion  it  gives  to  matter. 

There  are  not  differing  qualities  or  kinds  of  force,  which 
give,  —  this  kind,  circular  motion  to  bodies,  —  this  kind,  a 
straight  motion,  —  this  kind,  motion  in  a  contrary  direc- 
tion ;  nor  is  there  a  planetary  force,  and  a  molecular  force, 
and  an  oscillatory  force,  and  a  directly  acting  force ;  but 
the  one  force  may  act  on  any  element  of  matter,  moving  it 
in  any  direction,  which  idea  will  receive  further  illustration 
in  the  following  chapter. 

In  the  research  made,  the  general  propositions  were  ex- 
tended much  further  ;  but  up  to  this  point  only  were  they 
carried  with  that  distinctness  which  should  characterize 
such  propositions.  Others  remain  therefore  for  further 
examination. 


16  MECHANICAL    PHILOSOPHY. 

It  will  be  observed,  that  an  inquiry  like  the  preceding 
has  reference  to  force  mainly  as  in  action,  giving  to  mat- 
ter place,  position,  and  motion  in  reference  to  space, — 
actual,  and  not  apparent  or  relative  motion.  We  try  to 
consider  relative  motion  only  as  indicative  of  true  motion, 
and  this  as  indicative  of  the  laws  of  force.  Thus  the  ascent 
of  water  in  the  capillary  tube  is  regarded,  not  as  motion  in 
relation  to  the  tube  so  much  as  a  new  rotatory  orbit  of  the 
elevated  water.  The  log  line  which  is  veered  from  the  ship 
has  apparent  motion  of  its  own,  but  the  actual  motion  is  that 
of  the  ship.  This  distinction  we  would  recall  to  the  mind 
of  the  general  reader. 


CHAPTER  II. 


"WHEN  WE  HAVE  THE  DECREES  OF  NATURE,  AUTHORITY  GOES  FOR 
NOTHING."  —  Galileo. 


THE  errors  of  mechanical  philosophy,  if  there  are  errors, 
arise  from  the  assumption  of  gravitation,  or  the  attractive 
power  of  matter ;  from  the  application  of  the  law  of  the 
motion  of  falling  bodies,  to  the  uniform  motion  of  bodies 
remaining  in  one  determined  orbit ;  from  the  belief  that 
rectilinear  motion  is  the  natural  motion,  and  that  the  cur- 
vilinear is  a  constrained  motion  induced  by  conflicting 
forces  ;  and  from  keeping  out  of  sight  the  intense  motion  of 
every  atom  in  its  rotation  and  revolution  with  the  earth, 
which,  from  its  greater  comparative  velocity  supplies  the 
governing  or  controlling  motion,  and  by  reference  to  which 
alone,  incidental,  retarded,  or  accelerated  motion,  is  to  be 
understood  or  to  be  explained. 

In  the  illustration  of  our  views  we  shall  follow  no  artificial 
arrangement,  but  present  our  thoughts  in  the  order  in  which 
they  occurred  from  the  natural  connection  of  one  class  of 
facts  with  another  class  of  facts,  as  this  will  throw  more 
light  on  the  peculiar  views  than  any  predetermined  order  of 
investigation. 

Our  first  attempt  is  to  illustrate  the  idea  of  the  identity 
of  force,  —  to  prove  that  the  motive  power  of  nature  is  one, 
acting  under  uniform  laws  ;  that  force,  whether  it  form  the 

2* 


18  OUTLINES   OF  A   SYSTEM   OF 

dew-drop  or  marshal  the  "hosts  of  heaven,"  whether  it 
manifest  itself  in  the  flow  of  the  tides  or  of  the  purple  stream 
of  life,  whether  in  the  flash  of  lightning,  or  in  the  sweep  of 
the  bird  with  motionless  wing,  is  ever  the  same  principle  ; 
that  its  divisions  and  subdivisions,  its  ever-varying  names 
in  science  have  obscured  the  law  of  its  action,  and  thrown 
a  mist  over  philosophy  else  apparent,  from  the  ever-changing 
and  conflicting  theories. 

Of  the  nature  of  force  as  well  as  of  the  matter  it  moves, 
as  we  have  said,  we  are  entirely  ignorant,  and  from  the 
constitution  of  the  -mind  we  shall  forever  remain  ignorant. 
But  the  laws  of  its  action  given  to  it  from  the  beginning, 
and  ever  enduring,  may  perhaps  be  distinctly  traced  out 
and  understood.  Thus,  the  force  which  moves  the  spheres 
acts  under  the  intelligible  law,  that  velocity  is  in  proportion 
to  the  area  of  the  orbit,  that  with  the  diminution  of  distance 
from  the  centre  velocity  increases,  with  the  increase  of  dis- 
tance velocity  diminishes  ;  so  that  all  bodies  revolving  in 
free  space  describe  equal  areas  in  equal  times.  This  is  a 
property  of  orbitual  revolution,  —  in  other  words,  it  is  the 
property  of  force.  It  is  a  fixed  law,  subject  to  no  change. 
Aberrations  and  perturbations  are  temporary  and  oscilla- 
tory ;  the  mean  time  of  revolution  never  changes. 

The  revolution  of  the  heavenly  bodies  is  accompanied 
by  rotation  on  their  axis.  This  connection  of  the  primary 
with  the  secondary  movement  arises  from  another  law  of 
force,  —  from  another  property  of  the  power  which  imparts 
motion.  The  two  movements  appear  to  have  an  opposite 
character.  In  the  one,  as  we  have  seen,  velocity  in- 
creases by  the  diminution  of  the  orbit ;  in  the  other,  velo- 
city becomes  lessened  as  the  rotating  matter  approaches  the 
centre  of  rotation.  How  slow  the  rotation  of  the  central 


MECHANICAL  PHILOSOPHY.  19 

parts  of  the  earth,  while  at  the  equator  the  velocity  of  the 
surface  is  more  than  one  thousand  miles  an  hour  ! 

From  the  nature  of  the  rotating  sphere  there  is  one  fixed 
ratio  of  increase  of  the  velocity  of  its  parts.  Given  the 
velocity  at  any  distance  from  the  centre  of  rotation,  the 
velocity  at  any  other  distance  can  be  determined.  Its  ratio 
of  increase  is  proportional  to  the  increase  of  the  area  of  the 
circle  described.  We  have  the  same  measure  of  increase 
outward  in  rotation,  that  we  have  inward  in  revolution. 
The  primary  and  secondary  movements  are  under  the  same 
general  law.  Besides,  there  is  also  a  fixed  ratio  between  the 
velocities  of  both  movements,  for  such  is  the  far  pervading 
law  of  nature. 

If  the  orbit  of  any  planet  were  enlarged  without  additional 
force  of  propulsion,  it  would  move,  in  its  new  orbit,  with  de- 
creased velocity.  Its  motion  would  not  be  harmonic  ;  it 
would  not  describe  the  equal  area  of  planetary  motion.  To 
bring  it  into  harmonic  motion  it  would  require  additional 
force,  and  this  additional  force  needed  would  be  measurable 
by  the  increased  area  of  orbit.  If,  on  the  other  hand,  the 
orbit  of  any  planet  were  decreased,  with  the  same  propelling 
force  its  velocity  would  be  increased,  and  it  would  be  out  of 
harmony  with  its  associated  worlds.  With  equal  velo- 
city it  must  part  with,  or  transfer,  a  portion  of  its  force. 
This  degree  of  spare  force  would  also  be  measurable  by  the 
reduction  of  the  area  of  the  orbit.  The  degree  of  force 
required  or  imparted  is  not  measured  by  the  increase  or  dim- 
inution of  the  circumference.  The  orbit  does  not  measure 
velocity.  It  is  a  path  of  motion,  continuous,  without  be- 
ginning or  end.  By  a  fixed  law,  the  required  force  is 
determined  by  the  area  described,  which  increases  and 
diminishes  in  a  higher  ratio  than  the  length  of  the  circum- 


20  OUTLINES   OF   A   SYSTEM   OF 

ference  which  encloses  the  area.  Thus,  by  the  enlargement 
of  a  planet's  orbit,  it  would  need  added  force  to  preserve  the 
harmony  of  planetary  motion,  and  by  its  diminution  it  would 
impart  force,  and  the  force  added,  or  given  up,  would  be 
measurable  by  the  change  of  area.  In  the  words  of  Her- 
schell :  "  The  law  of  the  areas  determines  the  actual  velo- 
city of  the  revolving  body  at  every  point,  or  the  space  really 
run  over  by  it  in  any  given  portion  of  time.'7  If  the  velocity 
be  thus  determined,  so  is  the  present  force  which  determines 
the  velocity. 

This  is  equally  true  of  the  velocity  and  force  of  rotation. 
If  a  mass  at  the  surface  of  the  earth  be  elevated,  it  gains 
thereby  a  superior  level  of  rotation  ;  its  orbit  is  enlarged,  — 
it  requires  additional  force.  If  the  mass  fall,  thereby 
decreasing  its  orbit  of  rotation,  it  has  the  spare  force  of 
descent ;  it  requires  less  for  rotation,  and  the  falling  body 
imparts  force.  The  force  received  for  elevation,  the  force 
given  out  by  depression,  is  measured  in  one  case  by  the 
increase,  in  the  other  by  the  decrease,  of  the  area  of  the 
circle  of  rotation.  Though  in  one  view  it  appears  as  if 
there  were  the  converse  action  of  force,  yet  the  general 
kw  is  apparent,  of  the  increase  and  diminution  of  required 
force  for  any  area  of  orbit,  whether  acting  outwardly  from 
the  centre  or  inwardly  to  the  centre  of  revolution. 

The  identity  of  force,  acting  in  the  primary  movement  of 
the  spheres,  and  in  the  secondary  movement,  is  apparent, 
thus  considered,  and  a  general,  far-reaching  law  is  most 
clearly  indicated. 

The  force  which  moves  the  different  parts  of  the  earth  in 
rotation  differs  much  in  intensity.  How  small,  compara- 
tively, in  the  central  masses  at  the  axis  of  rotation ;  how 
great,  on  the  surface  of  the  earth  at  the  equator ;  how 


MECHANICAL  PHILOSOPHY.  21 

different  the  force  moving  the  surface  of  the  earth  at  the 
equator  from  the  force  moving  the  surface  of  the  earth  at 
the  poles  !  Yet,  the  weight  of  falling  bodies,  or  their  spare 
force  of  descent  is  nearly  the  same  at  the  equator  that  it  is 
at  the  poles. 

The  spare  force  of  descent  is  most  unquestionably  greater 
for  an  equal  change  of  orbit  at  the  equator  than  at  the  poles  ; 
but  the  change  of  the  area  of  the  orbit  is  far  less  by  the 
descent  of  one  foot  at  the  equator  than  it  is  at  a  distance 
from  the  equator.  As  we  go  from  the  equator  the  force 
of  rotation  lessens,  the  area  of  the  orbit  lessens  4n  that 
ratio  by  every  foot  of  descent,  so  that  the  increased  ratio  of 
the  decrease  of  area  compensates  for  the  decreased  force  of 
rotation.  Thus  have  we  an  equal  "  spare  force"  of  descent 
on  the  same  parallel  of  latitude,  slightly  increasing  as  we  go 
from  the  equator,  as  by  the  spheroidal  form  of  the  earth 
the  decrease  of  the  area  is  more  rapid  by  equal  decreases  of 
diameter,  in  proportion  as  the  earth  changes  from  the  perfect 
sphere  to  the  oblate  spheroid. 

There  is  not,  then,  one  law  of  force  for  the  revolution  of 
the  spheres,  and  another  for  their  rotation,  and  another  for 
the  changes  of  level  of  the  masses  composing  the  spheres  ; 
and  we  think  that  we  can  show  that  the  law,  by  which  the 
spheres  and  masses  are  moved,  also  directs  and  governs  the 
motion  of  the  atoms  composing  every  mass  and  sphere. 

The  spheres  lay  spread  out  before  us  as  distinct  objects 
of  conception.  From  the  immense  extent  of  space  they 
occupy,  and  the  almost  boundless  range  of  their  motion,  the 
law  of  force  indicated  by  them  becomes  intelligible,  and  is  the 
object  of  precise  reasoning  and  of  mathematical  calculation. 
If  we  would  understand  the  minute,  we  must  throw  upon  it 
the  light  gained  from  the  extended.  "  There  is  a  certain 


22  OUTLINES   OF   A   SYSTEM   OF 

character  or  style,  if  I  may  use  the  expression,  in  the  opera- 
tions of  Divine  Wisdom ;  something  which  everywhere  an- 
nounces amidst  an  infinite  variety  of  detail,  an  inimitable 
unity  and  harmony  of  design,  in  the  perception  of  which 
philosophical  sagacity  seems  chiefly  to  exist ;  "  or,  as  New- 
ton expressed  the  same  idea,  "  Nature  will  be  very  con- 
formable to  herself,  and  very  simple."  Thus,  no  less 
exact,  no  less  fixed  by  determinate  law  is  the  motion  of 
atoms,  and,  in  the  examination  of  the  minute,  this  idea  of  the 
extent  and  universality  of  primary  laws  should  be  ever 
present  to  the  mind. 

How  unlike  the  simplicity  of  nature,  her  directness  of  ac- 
tion, the  far-reaching  nature  of  her  laws,  is  the  array  of  op- 
posing and  conflicting  forces,  by  the  clashing  of  which  we  are 
taught  that  the  balance  or  equilibrium  of  things  is  preserved ! 
To  return  for  a  moment  to  the  spheres,  — -  there  is  the  im- 
pelling force,  the  repulsive  or  centrifugal  force,  the  attract- 
ive or  centripetal  force.  Of  what  use  are  these  ?  "  I  am 
persuaded,"  says  Plato,  "  that  if  the  earth  is  placed  in  the 
middle  of  the  heavens,  as  they  say  it  is,  it  stands  in  no  need 
of  air  or  any  other  support  to  prevent  its  fall ;  its  own 
equilibrium  will  keep  it  up.  For  whatever  is  equally  poised 
cannot  incline  to  either  side,  and  consequently  stands  firm 
and  immovable,  this  I  am  convinced  of."  If  the  centripetal 
and  centrifugal  forces  balance  each  other,  they  induce  no 
action  ;  give  the  earth  the  force  for  harmonic  motion  accord- 
ing to  her  orbit,  she  needs  neither  to  keep  her  in  the  track  ; 
there  would  be  no  danger  of  her  flying  off  in  a  tangent,  or 
of  her  falling  into  the  central  fires  of  the  sun ;  evenly 
balanced  with  them,  she  would  be  equally  balanced  without 
them. 

Why  these  conflicting  forces  were  created  by  philosophy 


MECHANICAL  PHILOSOPHY.  23 

is  very  apparent.  They  follow  from  the  strange  assumption 
that  nature  abhors  the  orbitual  or  curvilinear  motion  ;  that, 
in  the  words  of  Herschell,  "  A  straight  line,  dynamically 
speaking,  is  the  only  path  which  can  be  pursued  by  a  body 
absolutely  free,  and  under  the  action  of  no  external"  cor- 
rective "force."  Centrifugal  force  is  therefore  not  exactly 
a  force,  but  the  tendency  of  nature  to  escape  from  the  con- 
fined curvilinear  motion,  and  to  get  back  the  sphere  into  the 
straight  line  of  motion.  Philosophy  looks  upon  the  myriads 
of  rolling  spheres  as  in  unnatural,  constrained  movement, 
and  there  must  needs  be  conflicting  forces,  to  form  the 
grooves  and  channels  which  hedge  in  the  planets,  and  keep 
them  to  their  orbits,  when  they  would  so  rejoice  in  free 
straight  motion  to  the  bounds  of  space. 

Whewell  says  that,  "  In  cosmical  phenomena,  every 
thing  in  proportion  as  it  is  referred  tojpechanical  prin- 
ciples tends  to  simplicity,  to  permanent  and  uniform  forces, 
to  one  common  property.  In  magnetical  and  chemical 
appearances,  the  application  of  mechanical  principles  leads 
only  to  a  new  complexity  which  requires  a  new  explanation, 
and  this  explanation  involves  changeable  and  variable  forces, 
gradation  and  opposition  of  qualities."  That  is,  plain, 
simple,  mechanical  laws  apply  only  to  the  enlarged  action  of 
nature  ;  in  her  recesses  there  is  confusion,  unintelligibility. 
For  the  want,  therefore,  of  fixed  general  laws  in  the  minor 
mechanism  of  nature,  or  for  the  lack  of  comprehension  of 
those  laws,  the  department  of "  mechanico-chemical "  sciences 
is  cut  off  from  general  philosophy,  and  managed  by  a  great 
array  of  conflicting  forces,  such  as  heterogeneous  attraction, 
homogeneous  attraction,  capillary  attraction,  various  forms 
of  repulsion,  elasticity,  cohesion,  chemical  affinity,  current 
affinity,  and  the  forces  of  the  imponderables.  Every  judg- 


24  OUTLINES   OF  A   SYSTEM   OF 

ment  in  this  department  is  particular.  "  There  is  no  en- 
largement of  view  to  general  propositions."  We  see  deep 
thinking,  "  but  the  conclusions  arrived  at,  even  though 
clearly  expressed,  are  intricate  and  obscure."  There  is 
not  in  the  teachings  of  mechanico-chemical  science  the 
prominence,  the  boldness,  the  exactness;  the  simplicity, 
which  characterize  the  works  of  nature,  whether  her  force 
be  exerted  on  the  atom  or  on  the  world. 

Imponderables  are  so  called  because  they  are  not  the 
subject  of  weight.  They  impart  no  force  by  the  act  of 
descent,  but  for  this  reason  they  are  not  proved  to  be  imma- 
terial, without  matter.  We  read,  {London  EncyclopcedicC) 
that  "  a  stream  of  electric  fluid  issuing  from  points,  possesses 
force  sufficient  to  counteract  the  power  of  gravitation  in 
light  bodies" ;  ofcourse  the  imponderables  could  counteract 
the  gravity  of  any  matter  which  was  their  vehicle,  or  rather 
which  they  moved.  Gravity  being  the  unused  force  of 
rotation,  given  out  on  the  arrestation  of  the  motion  of  the 
falling  body,  they  have  none  of  this  spare  force  ;  they  can- 
not be  arrested ;  they  consume  all  their  inherent  force  in 
their  rapid  flight.  It  is  only  by  the  stopping  of  the  descend- 
ing motion  of  falling  bodies  that  they  give  out  force  or  indi- 
cate weight.  We  know  not  of  pure  disembodied  force,  and 
believe  that  the  imponderables  are  the  combination  of  force 
and  matter,  the  force  in  intense  degree  compared  with  the 
matter ;  that  the  element  of  matter,  and  its  quantity  in  the 
possession  of  force,  makes  the  distinctive  character  of  the 
imponderables,  and  that  force  is  thus  fitted  for  especial  func- 
tions in  the  economy  of  nature.  This  view  does  no  violence 
to  any  system  of  philosophy,  and  appears  demonstrable  by 
the  views  we  have  taken  in  the  preceding  propositions. 


MECHANICAL   PHILOSOPHY.  25 

First,  of  heat.  Heat  has  been  regarded  as  the  repulsive 
force,  as  the  diluent  of  force,  keeping  it  in  due  bounds. 
The  same  philosophers  who  would  set  aside  mechanical 
action  with  reference  to  the  mechanico-chemical  sciences,  at 
the  very  outset  bring  back  the  discharged  mechanical  laws. 
They  need  a  pendulum  or  balance  spring,  —  something  by 
which  to  regulate  and  control  the  mixture  of  forces.  Heat 
is  elected  to  this  office  of  antagonism.  The  perfect  law  of 
force  needs  not  this  restraint.  But  there  is  a  peculiarity  of 
the  action  of  force  under  the  condition  of  heat,  which  has- 
been  generally  referred  not  to  its  nature,  but  to  its  con- 
nected matter.  It  seems  fitted  thereby  more  especially  to 
induce  corpuscular  motion,  and  the  heat  acts  plainly  and 
distinctly  in  giving  consentaneous  motion  to  masses  ;  yet 
most  usually  its  effects  are  traced  in  an  internal  action. 

We  notice  in  this  place  the  difference  between  solar  and 
radiant,  or  reflected  heat.  The  passage  of  solar  heat  through 
a  lens  shows  that  force  then  has  under  its  control  matter, 
the  atoms  of  which  have  extent  of  surface,  as  will  be 
explained  when  we  refer  to  light.  Radiant  or  reflected 
heat  is  not  reflected  or  bent  by  the  passage  of  its  ray& 
through  a  glass  lens,  but  is  absorbed  by  the  glass,  which 
becomes  heated,  and  continues  so  until  by  conduction  the 
heat  is  equally  diffused.  It  appears,  then,  as  if  by  the 
impact  it  deposited  a  portion,  at  least,  of  its  accompanying 
matter,  and,  the  matter  being  deposited,  the  heat  in  passing, 
through  the  lens  is  absorbed.  The  force  has  taken  its  con- 
nection with  other  matter.  Radiant  heat  is  then  force  par- 
tially divested  of  its  matter  ;  partially,  we  say,  because  in. 
its  passage  through  a  lens  of  rock  salt,  it  again  obeys  the 
law  of  the  passage  of  light  and  heat  through  a  transparent 
media.  A  secondary  radiation  of  heat  still  further  deprives 
3 


26  OUTLINES   OF  A   SYSTEM   OF 

it  of  its  matter.  Thus  we  come  to  the  conclusion  that  these 
differences  are  caused  by  the  deposit  of  matter  at  the  im- 
pingement of  its  rajs.  It  shakes  off,  as  it  were,  its  imped- 
ing embodiment,  that  with  unimpaired  energy  it  may  give 
its  strength  to  the  corpuscular  movements. 

The  action  of  heat  is  readily  explained.  Every  species 
of  matter  has  that  quantity  or  degree  of  force  necessary  to 
maintain  its  atomic  structure.  This  is  called  latent  heat, 
and  is  latent  force.  Now  with  the  normal  degree  of  force 
in  molecular  action,  another  degree  of  heat  or  force  can 
be  received  and  made  latent  in  the  corpuscular  action 
without  apparent  change  of  structure.  This  is  specific 
heat ;  another  added  quantity  becomes  sensible  or  diffusible 
heat.  It  is  beyond  the  normal  heat  which  its  structure  can 
bear,  and  it  swells  or  enlarges.  Increase  the  heat  still  fur- 
ther,—  the  molecular  action  increases,  the  orbit  of  circula- 
tion enlarges,  and  the  solid  becomes  fluid  and  the  fluid  aeri- 
form. Hence  heat  acts  repulsively  by  the  very  law  which 
fixes  the  orbits  of  rolling  spheres,  that  of  increasing  cir- 
cles with  increasing  force.  "We  have  already  referred  to 
the  fact,  that  the  volume  of  the  dilating  body  increases 
three  times  in  small  bodies  for  its  length  of  increase,  indi- 
cating the  ever  circular  orbit  of  force.  Latent  heat  is 
therefore  normal  molecular  action,  capacity  for  heat,  that 
which  a  body  can  bear,  and  use  internally  without  change 
of  condition ;  sensible  heat  shows  itself  by  dilatation  and 
expansion,  by  the  increase  of  the  circular  motion  of  its 
atoms,  and  by  its  transfer. 

Daniell  says  that  the  polarity  of  heat  is  as  certainly 
demonstrated  as  the  polarity  of  light,  though  the  experi- 
ments which  demonstrate  it  are  of  a  more  delicate  nature. 
Polarity  is  circular  motion,  or  rather  the  indication  of  circu- 


MECHANICAL    PHILOSOPHY.  27 

lar  motion.  It  is  the  direction  of  the  orbit,  and,  applied  to 
matter  through  which  force  circulates,  the  poles  are  the 
anode  and  the  cathode, — 'the  direction  of  the  current  which 
passes ;  or  as  Whewell  describes  it :  "  Polarization  indicates 
opposite  properties  in  opposite  directions,  so  exactly  equal 
as  to  be  capable  of  accurately  neutralizing  each  other ;  that 
is,  the  same  force  passes  and  repasses  circularly  with  an 
even  power." 

Heat  is  always  accompanied  with  a  greater  or  less  degree 
of  light.  This  is  certain  with  reference  to  free  current  heat. 
Latent  heat  and  conducted  heat  are  not  the  subject  of  exam- 
ination ;  but  yet  as  the  breaking  up  of  cohesion  manifests 
light  with  the  evolved  heat,  it  appears  almost  certain  that 
light  is  the  essential  condition  of  force  manifesting  itself  as 
heat.  What  is  light  ?  Not  inert  sluggish  matter,  not  the 
disembodied  force  instantaneously  diffusing  itself,  but  the 
combination  of  the  two.  This  is  the  reason  of  the  endless 
disputes  about  the  materiality  and  immateriality  of  light ; 
both  views  are  partially  right,  both  are  wrong.  There 
are  indications  that  will  support  either  side  of  the  ques- 
tion, but  the  phenomena  collected  together  result  in  the 
union  of  the  two.  It  is  force  which  gives  it  its  transit,  its 
dynamical  laws  ;  it  is  matter  which  strikes  the  eye  and 
forms  the  picture  there.  It  is  what  force  transports  by 
which  the  world  is  painted  in  all  its  glory.  It  is  not  "  a 
propagated  quality  of  motion,  extending  in  right  lines  in  all 
directions  from  the  point  from  which  it  emanates ; "  but 
something  is  borne  along  on  the  wings  of  force  so  subtile 
as  to  be  felt  only  by  the  most  delicate  tissue  of  the  animal 
system,  the  retina. 

The  materiality  of  light  has  the  support  of  Newton  and 
the  great  philosophers  of  his  clay,  and  of  many  subsequently. 


28  OUTLINES   OF  A   SYSTEM   OF 

Its  materiality  seems  demonstrable  from  its  being  absorbed 
bj  the  vegetable  tissues,  giving  them  color  and  strength  of 
fibre  which  no  "  propagated  quality  of  motion  "  can  give. 
It  is  inherent  in  the  diamond ;  it  can  be  collected  from  the 
sun's  rays  by  solar  phosphori,  and  when  emanated,  the 
supply  can  be  again  received  by  a  fresh  exposure  to  the 
sun  ;  it  is  evolved  from  decaying  bodies  and  from  the  liv- 
ing animal  organization ;  it  obeys  the  laws  of  motion,  of 
known  moving  matter,  its  line  of  motion  is  bent,  and  when 
not  absorbed  by  the  body  on  which  it  impinges,  as  the  pon- 
derous missile  on  the  ice  or  water,  the  angle  of  reflection  is 
equal  to  the  angle  of  incidence. 

Light  also  changes  its  line  of  motion  in  passing  through 
a  denser  medium.  This  change  of  direction  is  only  at  its 
ingress  and  egress.  It  is  a  surface  change,  determined  not 
by  the  medium,  but  by  its  transit  within  and  without.  May 
not  this  be  the  theory  of  the  change  ?  The  atoms  of  light, 
being  matter,  have  extension  of  surface  ;  they  strike  the 
concave  or  convex  lens  on  their  edges  as  they  enter,  at  an 
angle,  not  with  their  surfaces  parallel  to  the  glass  ;  on  the 
egress  one  edge  escapes  while  the  opposite  is  yet  resisted 
by  the  denser  medium  ;  to  use  a  popularly  technical  word, 
they  are  canted  by  the  convex  towards  a  centre,  by  the  con- 
cave from  a  centre  or  focus,  both  on  entering  and  leaving 
the  glass.  It  appears,  too,  as  if  light  were  composed  of 
atoms  of  different  extensions,  as  by  the  prism  these  atoms 
are  separated  by  their  greater  or  less  impinging  surfaces. 
The  fall  of  a  flat  piece  of  wood  angularly  on  the  water  which 
would  be  turned,  illustrates  the  idea ;  in  the  case  of  the 
atom  of  light,  the  concave  or  convex  glass  would  make  the 
angle.  Does  not  this  also  explain  the  angle  of  reflection  ? 
It  is  remarkable,  too,  that  the  refractive  powers  of  media  are 


MECHANICAL    PHILOSOPHY.  29 

in  proportion  to  their  densities  ;  water  acts  more  powerfully 
than  air,  and  the  power  of  water  is  increased  by  its  having 
salt  in  solution.  Bring  to  the  mind,  too,  that  the  change  of 
direction  is  at  the  surface  only,  and  we  must  impute  it  to 
the  manner  of  its  entrance  by  surface  change.  A  wave  of 
ether  or  a  "  propagated  quality  "  of  motion  by  act  of  im- 
pingement would  accommodate  itself  to  the  angle  of  im- 
pingement, as  do  the  waters  of  the  ocean  to  the  projecting 
cliffs  of  the  shore.  The  theory  illustrates  the  phenomena, 
even  if  it  be  drawn  from  the  imagination  only. 

But  it  will  be  thought  that  our  view  is  too  mechanical 
and  rough  to  be  affirmed  of  light ;  for  how  exceedingly 
minute  must  be  those  particles  which  in  myriads  cross  and 
recross  without  impingement !  Space  is  indeed  incompre- 
hensible in  its  minute  divisions,  as  in  its  most  extended 
bounds.  It  seems  to  flow  out  on  either  side,  —  in  wave- 
like  undulations,  —  upon  the  confines  of  infinity,  with 
which  it  blends  without  distinctness  of  separation.  Obscure 
as  it  is  to  us  there  is  about  the  atom  room,  fixed  laws,  accu- 
racy of  motion,  and  to  higher  beings  the  laws  of  God, 
operating  in  a  mere  point,  may  be  as  palpably  distinct, 
as  to  us  is  the  waving  of  the  branches  of  the  tree  that 
bends  before  us  in  the  summer's  wind ;  and  because  the 
motion  of  the  atom  is  obscure  to  us,  must  we  throw  upon  it 
the  reflected  light  from  the  phenomena  which  nature,  in  her 
enlarged  sphere,  places  before  the  eye.  We  understand 
the  minute  only  as  we  comprehend  the  extended  ;  for  they 
both  have  the  one  God  over  them,  whose  law  is  universal, 
unchangeable  in  reference  to  the  atom  and  to  the  sphere. 

We  advert  but  to  one  more  of  the  phenomena  of  light,  — 
its  polarity  or  the  circular  motion  of  its  atoms.  This  is  the 
stamp  of  force,  its  great  characteristic,  ever  denoting  its 
3* 


30  OUTLINES    OF   A    SYSTEM    OF 

presence.  We  will  describe  polarization  in  the  words  of 
Daniell.  "  It  may  assist  our  comprehension  of  the  pheno- 
mena to  illustrate  them  by  a  rough  analogy  ;  a  ray  of  com- 
mon light  as  it  is  emitted  from  a  self-luminous  body,  we  may 
conceive  to  revolve  upon  an  axis  coincident  with  its  own 
direction,  as  a  cylindrical  rod  may  be  made  to  turn,  or 
which  comes  to  the  same  thing,  the  reflecting  or  refracting 
surface  may  be  made  actually  to  revolve  around  the  ray  as 
an  axis  preserving  the  same  relation  to  it,  and  no  change  in 
the  phenomena  will  be  perceived."  We  add,  that  the 
rolling  earth  flying  in  her  orbit  would  be  an  illustration 
perhaps  more  apposite. 

We  proceed  to  the  examination  of  electricity.  Franklin, 
with  the  sound  discrimination  which  characterized  his  mind, 
expressed  the  truth  in  relation  to  it.  We  will  quote  his 
language,  substituting  the  word  "  force  "  for  "  electrical 
fluid."  "  The  opposite  states  of  electrical  excitement  depend 
upon  the  increase  or  diminution  of  force  relatively  to  the 
two  bodies."  These  two  states  have  been  called  the  positive 
and  negative.  When  two  substances  are  rubbed  together, 
sometimes  the  one  and  sometimes  the  other  is  excited.  All 
substances  have  been  divided  into  electrics  and  dialectrics, 
the  one  the  conductors,  the  other  the  non-conductors  of  elec- 
tricity ;  but  subsequently  it  has  been  ascertained  that  all 
substances  are  conductors,  their  conducting  powers  differing 
only  in  degree.  Hence  we  have  not  conductors  and  non- 
conductors, but  substances  differing  in  being  good  or  bad 
conductors  ;  the  metals,  water,  animal  and  vegetable  bodies 
on  the  one  hand,  and  oil,  glass,  dry  air  on  the  other.  There 
is  in  the  extremes  a  striking  difference  of  atomic  structure, 
as  for  instance,  in  iron  and  spermaceti. 

Any  dissimilar  substances  rubbed  together  with  proper 


MECHANICAL  PHILOSOPHY.  31 

precautions  are  capable  of  exerting  the  power,  one  of  them 
becoming  excited.  The  effect  is  produced  by  the  applica- 
tion of  force,  nor  does  it  change  its  nature.  When  confined, 
it  is  force  ;  when  again  set  free,  it  is  force.  Electricity  is 
thus  described :  "  It  is  freely  evolved  by  the  mechanical 
action  of  heterogeneous  substances  ;  still  more  abundantly 
by  chemical  action  ;  it  is  a  product  of  animal  organization  ; 
it  is  capable  of  evolving  heat,  and  heat  is  capable  of  evolv- 
ing electricity.  It  is  capable  of  acting  on  bodies  in  oppo- 
sition to  gravity,  and  is  capable  of  the  most  energetic  action 
on  its  own  constituent  atoms.  Every  form  of  matter  may 
be  excited  to  its  action,  and  it  may  be  transferred  from  one 
portion  of  matter  in  which  it  has  been  called  forth,  to 
another  previously  in  its  natural  state."  We  could  not 
more  distinctly  describe  force.  Electricity  is  force  existing 
under  some  peculiar  conditions.  Its  polarity  is  one  of  its 
most  prominent  phenomena.  It  can  be  insulated,  or  a 
channel  formed  for  its  circulation  ;  it  can  be  kept  a  pris- 
oner, or  its  path  opened  that  it  may  return  to  the  earth, 
and  add  the  strength  of  its  feeble  stream  to  swell  the  torrent 
of  force  which '  bears  along  the  mighty  orb  in  her  rolling 
path. 

Differing  from  galvanism,  which  appears  as  a  continuous 
stream  of  force,  electricity  is,  as  it  were,  a  collected  mass, 
a  sphere  revolving  on  the  surface  of  the  glass.  It  does  not 
seem  to  affect  the  molecular  action,  but  to  pass  through  the 
aggregated  atoms  as  free,  revolving  in  its  own  orbit ;  for, 
if  you  break  the  cylinder  which  contains  it,  the  electrical 
spark  is  found  in  one  of  the  parts  only.  Electricity,  too, 
gives  another  striking  demonstration  of  its  nature.  We 
quote  :  "  If  the  electricity  collected  be  distributed  between 
balls  of  different  diameters,  it  will  be  found  that,  the  smaller 


32  OUTLINES   OF  A   SYSTEM   OF 

the  sphere,  the  more  intense  the  action."  Such  is  the  law 
of  force,  wherever  it  exists  ;  there  is  circular  motion,  equal- 
ity of  diffusion,  the  velocity  increasing  with  the  decrease  of 
the  diameter  of  the  orbit.  In  the  excited  rod,  too,  the  action 
is  more  intense  at  the  ends  than  at  the  centre  ;  for  the  law  is 
that  of  increased  speed  with  the  narrowing  diameter  of  the 
elliptical  orbit.  Electricity  gives  to  matter  no  attractive 
power,  —  as  it  partially  escapes  from  its  receptacle,  it  draws 
or  repels  other  bodies  towards  or  from  its  receptacle  ;  and 
whether  attracted  or  repelled,  the  moving  body  determines 
its  motion  by  its  own  state  of  excitement.  If  equally  ex- 
cited, it  adds  to  the  circulating  force  ;  if  less  excited,  it 
absorbs  a  part  of  the  circulating  force.  No  attraction  of 
matter  can  be  affirmed  of  this  fitful,  spasmodic  action  of 
bodies  floating  in  the  vortices  of  revolving  force.  How 
beautiful  the  provision  by  which  the  unexcited  body  advances 
to  the  excited,  then  in  contact  receives  its  burthen  to  be 
conveyed  to  other  bodies,  so  that  the  resultant  motion  of 
vertical  force  is  the  equal  distribution  of  that  force,  —  an 
equilibrium  preserved  not  by  opposing  forces,  but  by  the 
very  nature  and  laws  which  govern  the  action  of  force. 

Galvanism  is  the  result  of  the  breaking  up  of  existing 
structures,  thereby  freeing  the  force  which  bound  their 
atoms  together.  Would  any  one  ask  what  is  the  cement  of 
the  building  when,  by  its  destruction,  the  earth  is  covered 
and  the  air  filled  with  lime?  It  is  the  force  of  cohesion  made 
current,  which  constitutes  galvanism.  The  condition  of  its 
being  "  current  affinity"  is  decomposition,  and  a  conduct- 
ing circuit  or  orbit  in  which  it  is  to  move.  "  Now,"  says 
Daniell,  "  it  is  curious  to  observe  how  chemical  affinity  in 
all  these  experiments  waits  upon  the  conducting  and  col- 
lecting power  ;  the  strong  attraction  of  zinc  for  oxsulphion 


MECHANICAL    PHILOSOPHY.  33 

is  held  in  complete  check  till  a  passage  is  open  for  the  circu- 
lation of  the  force  ;  the  force  which  circulates  must  be  equal 
in  all  parts  of  its  circuit,  it  stops  with  the  slightest  break  in 
the  continuity  of  its  conductor."  Urged  sometimes  by 
the  intensity  of  the  charge,  it  leaps  through  a  short  space 
of  air,  and  then  with  its  flame  arched  upward,  proclaims 
the  tendency  of  force  to  assume  the  circle,  whose  circum- 
ference is  proportional  to  the  degree  of  the  force  which 
revolves. 

Dr.  Farraday  has  proved  that  the  contact  of  dissimilar 
metals  is  not  necessary  to  the  generation  of  the  current,  and 
that  the  force  is  always  in  exact  proportion  to  the  amount 
of  chemical  affinity.  With  a  knowledge  of  the  laws  of  force, 
this  fact  needed  not  the  demonstration  of  experiment ;  for 
the  force  of  cohesion  liberated  must  measure  the  current 
force  ready  to  act  in  new  combination,  or  to  pass  for  exam- 
ination along  the  conducting  wire  to  the  matter  it  is  to  bring 
together  in  newly  built  structures.  How  beautiful,  too,  the 
analogy  between  the  chemist  and  the  mechanic  ;  the  former, 
commanding  for  his  work  the  force  once  used  for  cohesion, 
and  again  directing  its  strength  for  a  similar  purpose ; 
the  latter,  using  as  his  property  the  force  of  a  moving 
world,  directing  it  in  the  circuit  of  his  machinery,  that  it 
may  destroy  structure  and  build  other  structures  that  min- 
ister to  human  wants.  This  very  analogy  has  been  thus 
traced  out.  "  The  analogy  of  the  transmission  and  direction 
of  mechanical  force,  may  perhaps  assist  in  the  formation  of 
a  clear  idea  of  this  influence  of  bodies,"  [current  affinity.] 
"  Every  one  is  familiar  with  the  modes  by  which  the  mus- 
cular force  of  animals,  the  elastic  force  of  steam,  &c.,  is  led 
by  the  solid  matter  of  levers,  cords,  and  wheels  to  distant 
points  from  its  source  arid  there  set  to  work,  somewhat  in 


34  OUTLINES   OF  A   SYSTEM   OF 

the  same  way  we  may  conceive  that  the  force  of  affinity  may 
be  directed  to  distant  points  through  appropriate  conductors. 
But  its  journey  ings  must  be  in  a  circle,  and  the  arrange- 
ment must  be  made  in  such  a  way  that  the  impulse  may 
return  to  the  point  from  which  it  set  out ;  it  must  circulate." 

"  In  no  case,"  says  Farraday,  "  is  there  a  pure  creation 
of  force,  a  production  of  power  without  the  exhaustion  of 
something  to  supply  it."  Of  course  it  has  excited  the  won- 
der of  chemists,  that  two  pieces  of  metal,  producing  no 
change  in  their  states,  should  be  an  inexhaustible  source  of 
power.  The  wonder  ceases  when  the  distinction  is  made 
between  current  affinity  brought  into  action,  and  continuing 
in  action  in  its  orbit,  and  the  current  affinity  from  broken 
cohesion,  returning  after  its  circuit  to  rebuild  from  the  ele- 
ments which  had  been  torn  asunder,  at  the  broken  orbit 
between  the  positive  and  negative  pole.  The  one  is  seen  in 
the  action  of  the  magnet,  —  the  other  in  the  passage  of  the 
galvanic  current,  passing  from  the  work  of  destruction 
through  the  wire  to  the  work  of  re-creation,  or  at  once 
passing  through  bodies  in  chemical  affinity. 

Before  we  proceed  to  the  examination  of  the  union  of  the 
magnetical  and  electrical  phenomena  and  the  action  of  the 
magnet,  we  will  explain  our  views  more  fully  of  the  effect  of 
the  galvanic  current  in  changing  the  condition  of  bodies  on 
which  it  acts.  Polarity  is  the  positive  and  negative  pole, 
or  the  direction  of  the  current  force.  The  wire  is  the  con- 
ducting circuit,  between  the  poles  of  which  is  the  substance 
acted  upon.  "  Now  the  idea  of  polarity,"  says  Whewell, 
"  involves  the  conception  of  opposite  properties  in  contrary 
directions  ;  for  example,  attraction  and  repulsion,  darkness 
and  light,  synthesis  and  analysis."  That  is,  force  revolves, 
the  current  in  its  passage  one  way  repels,  in  the  other 


MECHANICAL  PHILOSOPHY.  35 

attracts  ;  in  one  way  gives  darkness,  in  another  way  light ; 
it  breaks  down  structure  or  rebuilds  structure,  for  in  one 
way  force  is  taken  from  the  body  and  from  the  other  pole  it 
returns.  In  the  one  case,  for  instance,  it  resolves  water 
into  its  constituent  gases,  in  the  other  combines  the  ele- 
ments of  water  into  that  fluid.  This  proves  that  our  idea 
of  polarity  is  right,  and  opens  the  mystery  of  chemical 
action  generally ;  for  the  same  result  is  had  without  the 
wire,  —  the  transfer  of  force.  Farraday  expresses  the  idea 
in  almost  the  same  language.  "  Chemical  synthesis  and 
analysis  must  be  conceived  as  taking  place  by  virtue  of 
equal  and  opposite  forces,  by  which  the  particles  are  sepa- 
rated or  united,"  that  is,  by  the  transmission  of  force. 

We  continue  to  quote :  "  These  forces,  by  the  very  con- 
sideration of  their  being  polar,  may  be  transferred  from 
point  to  point,  and  thus  we  have  a  positive  force  active  at 
one  extremity  of  a  line  of  particles  corresponding  to  a  nega- 
tive force  at  the  other  extremity  ;  all  the  intermediate  par- 
ticles neutralize  each  other's  action.''  This  idea  was 
introduced  by  Prout,  confirmed  by  Davy,  and  fully  illus- 
trated by  Farraday  ;  and  for  its  full  comprehension  it  needs 
only  that  we  discharge  the  unmeaning  expression,  '  negative 
force,'  and  consider  the  phenomena  as  indicating  the  transfer 
of  force  in  its  circulating  orbit. 

In  our  view  of  magnetism,  we  have  the  labor  lessened  by 
the  acknowledged  fact,  that  current  affinity,  or  galvanism, 
or  electricity,  is  identical  with  magnetism.  It  is  so  decided 
by  competent  authority.  This  was  first  announced  by 
(Ersted  in  1820,  and  proved  by  a  series  of  experiments. 
Franklin  long  before  this  had  induced  magnetical  polarity 
in  fine  needles  by  passing  through  them  a  current  of  elec- 
tricity. The  disturbance  of  the  polarity  of  the  ship's  com- 
pass is  also  a  well  known  fact. 


36  OUTLINES    OF   A    SYSTEM   OF 

We  call  attention  to  this  phenomenon  :  place  the  needle 
over  the  conducting  wire  ;  it  lies  across  the  path  of  the 
rushing  force  ;  beneath,  it  lies  again  across  the  marked  pole 
in  the  contrary  direction.  Dr.  Farraday  succeeded  in  pro- 
ducing a  revolution  of  the  needle  about  the  wire,  and  of  the 
wire  around  the  needle.  The  principal  effects  of  terrestrial 
magnetism  "  may  be  imitated  by  distributing  a  wire  around 
the  surface  of  an  artificial  globe,  in  a  spiral  direction  from 
the  equator  to  the  poles,  the  two  extremities  being  turned 
inwards,  brought  out  at  the  two  axes,  by  which  the  connec- 
tion may  be  made  with  the  battery.  A  magnetic  needle 
properly  suspended  in  different  situations  near  the  globe, 
will  arrange  itself  in  positions  perfectly  analogous  to  those 
assumed  by  the  dipping  needle  in  the  corresponding  regions 
of  the  earth."  The  action  of  conducting  wires  rolled  in  the 
form  of  the  flat  spiral,  produces  on  one  side  the  action  of 
the  marked  (north)  pole,  and  on  the  other  of  the  unmarked 
pole  of  the  magnet. 

As  it  has  been  remarked,  this  is  the  fundamental  fact, 
(the  rotary  movement  accompanying  the  orbitual,)  to  which 
other  facts  of  eZe<?£r0-magnetism  are  reducible.  Magnetic 
bodies  derive  their  power  of  attraction  from  the  circular 
movement  of  force.  Within  them,  extending  beyond  them 
to  bodies  of  similar  nature  within  certain  distances,  the  po- 
larity of  magnetical  bodies  is  owing  to  the  secondary  or 
rotative  current  which  invariably  accompanies  what  may  be 
termed  the  primary  motion  of  force. 

Thu-s  is  the  polarity  of  the  needle  upon  the  surface  of  the 
globe  indicative  of  a  current  of  force  circulating  around  the 
globe  in  planes  parallel  to  the  magnetic  equator,  increasing 
in  power  from  the  equator  to  the  poles,  obeying  the  general 
law,  increase  of  intensity  with  decrease  of  the  orbit.  M. 


MECHANICAL  PHILOSOPHY.  37 

Ampere  was  the  first  who  recognized  the  existence  of  this 
current,  which  has  been  imputed  to  the  influence  of  the  sun 
upon  the  tropical  regions.  That  the  current  flows  there  is 
no  doubt ;  the  finger  guide,  the  magnet,  is  authority  ;  and  it 
not  only  indicates  the  fact,  to  which  we  shall  often  refer, 
but,  what  is  more  important,  points  to  a  principle  of  universal 
application, — the  onward  primary  movement  of  force  is 
always  accompanied  by  the  secondary.  Thus  orbitual  and 
rotary  movement  as  the  law  of  force  is  affirmed  not  only  by 
the  movements  of  the  spheres,  but  by  every  rivulet  of  force 
which  has  strayed  from  the  mighty  channel  of  power,  —  to 
be  predicated,  not  only  of  the  career  of  worlds,  but  of  the 
action  of  the  most  minute  particles  of  matter. 

The  preceding  remarks  also  indicate  the  action  of  force 
upon  the  magnet.  By  the  touch  of  the  loadstone  there  is 
given  to  the  atoms  of  the  needle  the  structure,  which  deter- 
mines the  flow  of  force  through  it  in  a  fixed  orbit.  Force 
in  any  other  direction  gives  motion  to  the  needle  on  its 
pivot ;  force  in  the  direction  of  this  orbit  flows  through  it, 
and  it  is  unmoved  by  it.  Thus  it  oscillates,  a  motion  never 
produced  by  a  stationary  fixed  force,  but  by  the  absorption 
and  transfer  of  force.  In  one  direction  force  gives  motion 
to  the  needle  ;  in  another  direction  the  force  flows  through 
it,  presenting  a  perfect  analogy  to  the  oscillations  of  the 
pendulum.  This  idea  will  be  explained  as  we  proceed. 

The  attractive  power  of  the  magnet  may  be  understood 
from  the  process  of  inducing  magnetism.  Dispose  of  two 
bars  of  steel  in  a  parallelogram,  connect  them  at  the  ends 
with  two  pieces  of  soft  iron,  thus  making  a  circuit  or  orbit 
for  force,  and  apply  the  loadstone;  or  in  a  horseshoe  magnet 
connect  the  extremities  by  a  piece  of  soft  iron,  making  the 
circuit,  and  then  apply  the  force  through  the  medium  of  the 
4 


38  OUTLINES    OE   A    SYSTEM   OF 

loadstone.  Thus  you  have  polarity,  —  a  direction  of  the  cir- 
culatory force.  The  keeper,  as  the  piece  of  soft  iron  is 
called,  when  attached,  is  a  part  of  the  orbit,  and,  while  it  is 
attached,  the  circuit  of  force  being  complete,  the  magnet  has 
almost  no  attractive  power.  Remove  it,  and  iron,  a  sub- 
stance resembling  steel  in  its  structure,  will  be  brought  by 
force  to  finish  out  the  broken  orbit.  If  the  loadstone  be 
applied  to  a  circular  piece  of  steel,  magnetism  is  as  truly 
induced,  but  force  revolves  latent  and  unobserved.  Such  is 
the  delicacy  of  the  established  orbit,  that  a  fall  upon  the 
floor  will  often  materially  affect  the  power  of  the  magnet ; 
and  magnets,  to  have  their  power  preserved,  should  be  laid 
away  with  the  keeper,  that  is,  with  the  completed  orbit. 
Some  additional  facts  will  throw  more  light  on  this  subject. 
The  concussion  of  the  steel  by  a  hammer,  causing  it  to  vi- 
brate strongly,  will  aid  the  process  of  inducing  magnetism. 
Thus  force  is  supplied,  or  the  molecular  movement  enables 
the  atoms  to  arrange  themselves  in  the  line  for  the  orbit. 
After  the  orbit  is  established,  a  sudden  jar  may  disarrange 
it,  by  excess  of  atomic  motion  ;  and  oxygen,  uniformly  the 
destroyer  of  structure,  always  annihilates  the  orbit. 

An  unlettered  man,  on  looking  at  the  action  of  a  magnet, 
exclaimed,  Why,  it  appears  as  if  it  let  out  a  loop  of  cord  to 
draw  something  into  its  place.  Well  did  he  indicate  the  action 
of  force  in  completing  its  orbit,  and  changing  it  from  the 
elliptical  to  the  circular.  Many  attempts  have  been  made 
to  convert  the  magnetical  force  into  motive  power  for  eco- 
nomical purposes.  In  vain ;  and  the  reason  given  for  the 
failure  is,  the  short  distance  at  which  magnetic  force  can 
be  made  to  act.  But  a  more  general  principle  is  the  cause 
of  the  disappointment,  —  one  which,  when  understood,  will 
prevent  any  further  attempt.  The  action  is  such  as  itself 


MECHANICAL  PHILOSOPHY.  39 

to  complete  the  circuit,  and  the  revolving  interior  force  is 
locked  up,  giving  cohesion  to  the  mass.  The  completed 
orbit  of  the  magnetic  force  is  beautifully  illustrated  by 
pieces  of  fine  wire,  cut  in  lengths  of  about  1-8  inch,  which 
may  be  suspended  from  the  magnet,  forming  a  chain  or 
connected  loop  from  one  pole  to  the  other.  The  soft  iron 
receives  polarity  by  this  contact  without  the  power  of  retain- 
ing it,  except  when  the  circulation  is  maintained  by  the 
permanent  magnetic  structure  of  the  steel.  We  notice,  too, 
the  accumulation  of  intensity  at  the  ends  of  the  magnetic 
bar,  the  ellipticity  of  the  orbit  developing  as  ever  the 
increased  velocity  of  force,  just  as  the  comet  is  drawn  with 
accelerated  speed  in  the  sharpest  part  of  its  elliptic  course. 

We  notice  in  this  place,  as  an  idea  growing  out  of  the 
preceding,  the  difference  of  structure  between  the  electric 
and  the  dielectric,  the  good  and  the  bad  conductors  of  force. 
In  a  strong  metallic  conductor  the  force  condenses  itself, 
increasing  in  intensity  with  the  decrease  of  its  orbit,  —  in 
other  words,  in  the  electric  it  establishes  its  orbit ;  while  in 
the  dielectric  the  orbits  for  circulation  do  not  exist,  or  feebly 
exist.  Says  Daniell,  "  In  the  dielectric  the  force  cannot 
travel  from  one  end  to  the  other  to  accumulate  at  the  ends, 
like  the  electric  forces  in  the  insulated  conductor."  We 
refer  to  this  fact  now,  as  it  throws  light  upon  the  action  of 
imponderables,  for  instance,  force  destroying  wood,  while  it 
enlarges  iron  ;  but  mainly  because  this  distinction  will  add 
much  clearness  to  our  conception  of  the  important  conditions 
of  mechanical  action  in  the  pressure  and  friction  of  bodies 
in  contact. 

Whence  is  animal  force  ?  We  are  prepared  in  some  de- 
gree at  least  to  detect  its  source,  if  it  lie  not  too  deep  in 
the  mysteries  of  the  living  organization.  The  proximate 


40  OUTLINES    OF   A    SYSTEM   OF 

cause  of  animal  heat  (force)  is  unquestionably  respira- 
tion ;  but  physiology  has  not  yet  arrived  at  a  distinct  enuncia- 
tion of  the  principle,  by  which  the  change  in  the  condition 
of  the  inhaled  and  exhaled  air  deposits  force.  It  is  pre- 
sumed that  it  is  the  breaking  up  of  animal  tissues,  which 
are  exhaled  as  the  base  of  carbonic  acid.  This  slow  com- 
bustion, it  is  said,  evolves  heat. 

The  accelerated  action  of  the  lungs  by  the  need  of  force  for 
unwonted  exertion,  and  the  continuous  full  play  of  the  lungs 
as  denoting  permanent  strength,  tell  us  as  plainly  as  facts 
can  speak  that  force  comes  proportionally  to  the  act  of  res- 
piration. If  our  general  view  be  correct,  we  shall  find  that 
the  air  has  parted  with  force  on  its  contact  with  the  lungs. 
It  is  even  so.  The  air  expired  is  heavier  than  when  in- 
haled. It  has  been  deprived  of  force.  The  formation  of 
carbonic  acid  is  not  only  the  principle  of  heat,  but  the  con- 
dition of  the  force  of  life  in  all  organic  structure.  The 
reason  of  its  transfer  of  force  to  the  blood,  and  through  it  to 
all  the  separate  parts  of  the  system,  is  only  to  be  known  by 
understanding  the  nature  of  life,  which  is  perhaps  wrapped  in 
obscurity  by  the  very  belief  that  its  mysteries  are  inscruta- 
ble. But  should  we  ever  admit  that  any  thing  which  bears 
the  stamp  of  the  finite  is  unintelligible  ? 

Animal  force  develops  itself  under  the  conditions  of  heat, 
light,  electricity,  galvanism,  and,  it  is  said,  of  magnetism. 
It  is  circular  in  its  flow  through  the  system ;  the  heart  and 
brain  establish  its  polarity  or  direction.  Electricity  and 
galvanism  will  move  the  muscles,  taking  the  place  of  the 
muscular  force. 

Do  we  wish  for  more  proof  of  the  identity  of  heat,  cur- 
rent affinity,  galvanism,  muscular  force,  of  all  and  every 
form  of  power  ?  If  you  elevate  a  body  to  make  it  rotate  at 


MECHANICAL  PHILOSOPHY.  41 

a  higher  level  from  the  earth,  thereby  increasing  the  cir- 
cumference of  the  circle  it  must  describe,  will  not  either 
and  all  of  them  give  to  the  body  elevated  its  required  force  ? 
Are  not  each  and  all  of  them  resolvable  into  the  force  which 
moves  the  spheres  ? 

We  have  passed  over  this  examination  of  the  streams  of 
force  with  a  hurried  glance.  If  these  excite  our  wonder 
and  admiration,  what  is  the  feeling  with  which  we  fix  our 
attention  on  the  fountain  itself,  from  which  these  come  as 
the  accidental  spray  and  tossing  of  the  ocean  ever  spread 
out  before  us,  —  the  force  which  moves  the  system  of 
systems,  the  creation  of  an  eternal  and  almighty  God,  re- 
volving in  circle  upon  circle  through  limitless  space.  We 
stand  speechless  at  the  thought  of  this  boundless  power  up- 
holding the  heavens  and  the  earths  ;  yet  boundless  as  it  is, 
the  strength  of  creation  softly  and  kindly  ministering  to  the 
breath  of  the  sleeping  child ! 

Whewell  expresses  the  idea  of  the  identity  of  force  in 
the  one  hundred  and  third  aphorism  of  the  Philosophy  of 
the  Inductive  Sciences,  in  these  words :  "  Mechanical, 
chemical,  and  vital  forces  form  an  ascending  progression, 
each  including  the  preceding.  Chemical  affinity  includes 
in  its  nature  mechanical  force,  and  may  be  often  practically 
resolved  into  mechanical  force,"  &c.  Chemists  generally 
indicate  the  identity  of  force  by  their  communication  of  the 
fact,  that  the  same  matter  in  its  atomic  divisions  has  the 
same  affinity  for  gravitation,  for  heat,  and  for  electricity. 
Thus  is  pointed  out,  analytically  as  well  as  synthetically,  the 
identity  of  force.  We  need  not  enlarge,  as  every  chemical 
manual  gives  the  results,  and  it  would  be  the  mere  task  of 
the  copyist,  transferring  the  sentences  of  the  common  books 
on  the  science  of  chemistry. 


42  OUTLINES    OF   A   SYSTEM   OF 

"  We  find,"  says  Humboldt,  "  among  the  most  savage 
nations,  as  my  own  travels  enable  me  to  attest,  a  certain 
vague,  terror-stricken  sense  of  the  all-powerful  unity  of 
natural  forces,  and  of  the  existence  of  an  invisible  essence 
manifested  in  these  forces,  —  whether  in  unfolding  the 
flower  and  maturing  the  fruit,  in  upheaving  the  soil  of  the 
forest,  or  in  rending  the  clouds  with  the  force  of  the  storm. 
We  may  here  trace  the  revelation  of  a  bond  of  union,  link- 
ing together  the  visible  world  and  that  higher  spiritual  world 
which  escapes  the  grasp  of  the  senses.  The  two  become 
unconsciously  blended  together,  developing  as  a  simple  pro- 
duct of  ideal  conception  the  first  germ  of  a  philosophy  of 
nature." 

The  great  error  of  science  is  its  too  minute  classification 
of  facts,  and  the  attempt  to  find  for  each  class  of  fact  a  dis- 
tinct and  definite  law.  Facts  are  never  isolated  ;  there  are, 
in  philosophy,  no  lines  of  demarcation  between  them.  It  is 
the  poverty  of  man's  intellect  that  thus  subdivides.  .Take, 
for  instance,  the  classes,  departments,  orders,  kingdoms  of 
organic  structure.  How  they  fade  away  one  into  the  other ! 
How  clear  on  this  point  is  Agassiz,  in  his  Philosophy  of 
Natural  History !  Other  strong  minds  follow  his  investiga- 
tions. He  does  not  look  upon  organic  structure  only  as  a 
succession  of  classes  ;  he  does  not  affirm  laws  of  local  or  of 
special  application  alone.  He  views  life  as  a  whole,  and 
sees  the  general  law  which  gives  a  oneness  to  creation. 
He  combines  when  others  analyze  ;  he  looks  for  simplicity 
where  others  see  diversity.  How  true  is  the  law  of  the  mind 
to  the  law  of  nature  !  The  pure  conception  of  the  savage 
seizes  the  idea  of  the  unity  of  nature,  and  the  truly  great 
philosopher  offers  the  same  as  the  deduction  of  the  reason- 
ing power.  It  is  in  an  intermediate  order  of  minds  that  we 


v^ 

MECHANICAL    PHILOSOPHY.  43 


find  the  errors,  the  accumulation  of  unassorted  facts,  the 
confusion  of  conflicting  theories.  The  first  thought,  natural 
to  the  mind,  is  unity,  —  the  last  and  highest  conceptions 
return  to  the  thought  of  the  pure  and  simple  reason. 


CHAPTER  III. 


"PHYSICS  DISCOVERS  CAUSES    FROM  THEIR  EFFECTS   AND  EFFECTS 

FROM   THEIR   CAUSES." — St.     Victor, 

CUKSOBILY  must  we  pass  through  our  examination  of 
capillary  attraction,  heterogeneous  and  homogeneous  at- 
traction and  repulsion,  and  chemical  affinity  ;  cursorily,  be- 
cause we  need  not  devote  attention  to  the  minor  phenomena, 
as  the  consideration  of  the  more  prominent  involves  that 
of  the  lesser ;  for  general  laws  grasp  the  points,  however 
minute,  as  well  as  embrace  the  aggregate  of  points  which 
constitute  the  universe,  force  under  general  laws  determin- 
ing the  place  and  position  of  all  things,  the  minute  as  well 
as  the  extended. 

It  is  sympathetic  motion  which  forms  the  continuity  of 
worlds ;  and  if  a  mass  be  formed,  it  is  also  by  sympathy  of  the 
motion  of  its  parts,  —  it  exists  as  a  mass  by  this  sympathy  of 
motion, — if  it  be  rent  asunder,  it  is  by  jarring  and  conflicting 
motion.  If  there  were  not  harmony  of  motion  among  the 
spheres,  the  solar  system  could  not  exist.  If  there  were  not 
sympathy  of  motion  among  atoms,  masses  could  not  exist. 
From  this  latter  idea  are  deducible  homogeneous  and  hetero- 
geneous attraction,  the  phenomena  of  filtration,  of  exosmose 
and  endosrnose,  and  generally  the  attraction  and  repulsion 
of  bodies  at  distances  not  too  remote  for  their  reciprocal 
action  on  each  other  through  the  connecting  media  of  air, 
water,  or  other  substances. 


45 

Capillary  attraction  is  certainly  inexplicable  on  the  ground 
of  the  attraction  of  matter.  As  generally  understood,  mat-' 
ter  attracts  in  proportion  to  its  bulk.  But  water,  attracted 
by  the  thin  glass  tube,  escapes  from  the  attraction  of  the 
earth  which  retains  its  hold  upon  the  glass  tube,  yet  lets 
the  flowing  water  elude  its  grasp,  and  run  up  in  perfect  in- 
dependence. But  the  centre  of  the  glass  tube  has  no  more 
attracting  power  than  the  ends  ;  and,  if  the  glass  be  filled 
with  water,  the  tube  ought  to  attract  downward  as  well  as 
upward.  Indeed  there  is  in  this  phenomenon  not  one  soli- 
tary fact  to  show  that  the  glass  attracts  the  water,  except 
that  the  water  in  the  tube  is  concave,  rising  where  in  contact 
with  the  glass ;  nor  does  this  manifest  the  attraction  of  the 
glass,  but  an  attraction  upward.  Surely  if  the  sides  of  the 
glass  attracted,  the  area  under  the  surface  would  attract 
downward  as  well  as  the  area  above  attract  upward.  Per- 
haps wetting  the  bore  of  the  glass  takes  away  the  power 
of  attraction ! 

It  has  been  remarked  that  "  the  boldest  imagination  can 
hardly  form  a  conception  of  the  undulations  rendered  latent 
without  annihilation,  laid  up  in  store  as  it  were,  and  capable 
of  being  drawn  forth  in  full  measure  and  intensity."  This 
appears  to  be  the  idea  which  leads  to  the  understanding  of 
the  phenomena  of  capillary  attraction.  These  undulations, 
latent  in  the  water,  are  brought  into  the  consentaneous  mo- 
tion of  the  mass  inclosed  in  the  narrow  tube.  It  appears  as 
if  the  range  of  molecular  action  were  reduced  by  the  con- 
finement, and  the  no  longer  used  atomic  force  is  resolved 
into  rotative  force  at  a  higher  level.  In  mercury,  the  action 
is  perhaps  the  converse ;  the  atomic  force  of  the  glass  may 
be  increased,  and  force  be  withdrawn  from  the  fluid  metal. 
We  thus  offer  a  more  consistent  theory  than  the  old  theory, 


46  OUTLINES   OF  A   SYSTEM   OF 

even  if  it  be  not  true,  and  its  truth  may  be  rendered  more 
apparent  by  our  proposed  examination  of  the  properties  of 
fluids. 

We  read,  however,  that  "  it  has  been  proved  by  experi- 
ment that  mercury  will  rise  above  its  level  in  the  same  man- 
ner as  water,  when  both  the  tube  and  mercury  are  per- 
fectly dry.  The  mercury  being  dried  by  repeated  boiling, 
is  freed  from  its  humidity.  It  appears,  therefore,  that  the 
depression  of  the  mercury  below  the  level  is  occasioned  by 
a  little  moist  film,  which  attaches  itself  to  the  interior  sur- 
face of  the  glass,  and  thus  by  its  interposition,  perceptibly 
weakens  the  attractive  force  of  the  glass,"  &c.  The  effect 
on  the  phenomena  of  capillary  attraction  will  be  further 
elucidated  in  the  prosecution  of  this  inquiry.  One  thing  is 
certain,  the  rise  of  water  is  not  from  the  attraction  of  the 
glass ;  for  the  glass  would  attract  downward  as  well  as 
upward,  especially  as  aided  by  the  attraction  of  the  earth. 
It  has  been  supposed  that  the  ring  of  glass  above  the  sur- 
face is  the  attractive  cause.  By  others,  as  by  Dr.  Hamilton, 
"  that  the  fluid  is  supported  by  the  attraction  of  the  annulus 
contiguous  to  the  bottom  of  the  tube."  The  bulk  of  sup- 
ported fluid  is  not  proportional  to  the  surface  of  the  glass 
with  which  the  fluid  is  in  contact.  Of  course,  "  gravitation  " 
in  capillary  attraction  is  out  of  the  question. 

Elasticity  is  the  property  of  bodies,  the  particles  of  which 
have  a  wider  space  and  larger  vibrations,  which  vibrations 
can  be  lessened  for  the  time  by  the  application  of  outward 
force.  Glass,  for  instance,  is  extremely  elastic,  and  the 
wide  separation  of  its  atoms  gives  it,  probably,  its  transpa- 
rency, and  perhaps  its  peculiar  properties  in  relation  to 
electricity.  Air  is  highly  elastic,  and  is  distinguished  by  the 
readiness  with  which  it  receives  and  transports  the  vibra- 


MECHANICAL  PHILOSOPHY.  47 

tion  of  denser  media  of  force.  It  acts  as  the  conveyer 
of  motion,  as  the  distributor  of  power,  trembling  before  the 
least  impulse,  yet  spreading  out  the  vibration  in  every 
direction,  till  the  moving  force  is  equally  distributed  and 
the  equilibrium  is  again  restored. 

Cohesion  is  supposed  to  be  a  branch  of  the  attractive 
force  of  matter.  This  force,  it  is  said,  "  connects  the  par- 
ticles of  bodies  together  in  the  solid  form  with  greater  or 
less  energy."  To  increase  or  diminish  this  force  so  as  to 
keep  the  particles  from  actual  contact  in  adamantine  hard- 
ness, and  to  give  the  different  energies  of  cohesive  power, 
an  antagonist  power  is  imagined,  the  repulsive  force  of  mat- 
ter, "  separating  the  particles  of  bodies  from  each  other  with 
greater  or  less  energy."  Like  Mahomet's  coffin,  the  atom 
hangs  midway  in  the  rest  of  perfect  equilibrium.  But, 
alas  !  bodies  in  equilibria  move  at  the  softest  touch,  and  the 
particles  of  the  solid  iron  would  tremblingly  oscillate  as  the 
slightest  breath  of  wind  passed  over  them. 

A  better  knowledge  of  the  action  of  current  affinity, 
that  is,  the  acknowledgment  of  the  laws  of  force  developed 
by  the  recent  experiments  of  distinguished  chemists,  has 
led  to  the  supposition  that  cohesion  is  induced  by  the  revo- 
lution of  electrical  force  through  the  mass,  though  the  belief 
is  not  yet  generally  or  distinctly  avowed.  "  Schelling,  in 
1803,  says,"  • — we  quote  from  Whewell, — "  magnetism  is  the 
universal  act  of  investing  multiplicity  with  unity."  Accord- 
ingly we  find  Schelling  welcoming,  with  a  due  sense  of  their 
importance,  the  discoveries  of  Farraday :  "  When  he  heard 
of  the  experiment  in  which  electricity  was  produced  from 
common  magnetism,"  he  thus  reasoned;  —  "we  have  three 
effects  of  polar  forces,  —  electro-chemical  decomposition, 
electrical  action,  magnetism.  Volta  and  Davy  had  con- 


48  OUTLINES    OF   A    SYSTEM   OF 

firmed  experimentally  the  identity  of  the  two  former  agen- 
cies ;  (Ersted  showed  that  a  closed  Voltaic  circuit  acquired 
magnetic  properties  ;  but  in  order  to  exhibit  the  identity  of 
electric  and  magnetic  action,  it  was  requisite  that  electric 
force  should  be  extricated  from  magnetic.  This  great  step, 
he  remarked,  Farraday  had  made  in  producing  the  electric 
spark  by  means  of  the  magnet."  Whewell  continues, — 
"  Although  conjectures  and  assertions  of  the  kind  thus  put 
forth  involve  a  persuasion  of  the  pervading  influence  and 
connection  of  polarities,  which  persuasion  has  already  been 
confirmed  in  many  instances,  they  involve  this  principle  in 
a  manner  so  vague  and  ambiguous,  that  it  can  rarely  in 
such  a  form  be  of  any  use  or  value."  From  the  opinion  of 
one  so  distinguished  by  reasoning  power,  it  is  perhaps  pre- 
sumption to  differ ;  but  it  is  deemed  that  polarity,  or  in  other 
words,  circulating  bands  of  force  are  the  only  possible  tie 
for  continuity  of  mass,  for  the  connecting  bonds  of  the  solar 
system,  for,  —  in  the  words  of  Schelling, —  "  the  act  of  in- 
vesting multiplicity  with  unity."  We  will  give  our  reasons 
for  this  opinion  as  they  have  occurred  to  us. 

There  has  been  established  a  connection  between  magnetic, 
electrical,  and  optical,  and  between  these  and  crystalline  po- 
larity ;  and  crystallization  is  the  taking  up  of  the  bond  of  the 
cohesion  of  solids.  Bodies  never  crystallize,  except  when 
their  elements  combine  chemically,  and  solid  bodies  which 
combine,  when  they  do  it  most  completely  and  exactly,  also 
crystallize.  The  forces  which  hold  together  the  elements  of 
a  crystal  of  alum  are  the  same  forces  which  make  it  a 
crystal.  There  is  no  distinguishing  between  the  two  sets 
of  forces.  Accordingly,  Berzelius  asserts  that  the  regular 
forms  of  bodies  suppose  a  polarity,  which  can  be  no  other 
than  the  electrical  or  magnetic  polarity.  Again  ;  "  the 


MECHANICAL    PHILOSOPHY.  49 

identity  of  a  crystalline  and  optical  polarity  is  too  obvious 
to  need  insisting  on."  Thus  much  from  authority  of  these 
latter  days  ;  and  we  quote  the  words  of  Newton  :  "  Would 
it  were  permitted  us  to  deduce  the  other  phenomena  of  na- 
ture from  mechanical  principles,  and  by  the  same  kind  of 
reasoning ;  for  many  things  lead  me  to  suspect  that  all  these 
phenomena  depend  on  certain  forces  by  which  the  particles 
of  bodies  are  either  urged  toward  each  other,  through 
causes  not  yet  known,  and  cohere  according  to  regular  fig- 
ures, or  are  repelled  and  recede  from  each  other ;  which 
forces  being  unknown,  philosophers  have  hitherto  made 
their  attempts  upon  nature  in  vain." 

We  are  disposed  to  believe  that  the  ultimate  particles  of 
bodies  have  an  orbital  or  rotary  motion,  intense  in  propor- 
tion to  the  circumscribed  space  in  which  they  move.  In 
every  mass,  also,  and  at  times  extending  beyond  the  mass", 
(as  especially  the  object  of  perception  in  the  magnet,)  this 
motion  exists,  the  phenomena  of  which  are  those  of  polariza- 
tion, and  the  result  of  which  is  cohesion  together  with  the 
phenomena  of  friction,  and  perhaps  of  chemical  affinity. 
The  force  revolving  in  the  mass  is  cohesion,  out  of  the  mass 
friction  or  pressure,  and  the  change  of  the  structure  of  the 
mass  is  chemical  action.  These  ideas  we  will  attempt  to 
develop. 

The  magnet,  which  by  its  polarity  indicates  the  passage 
of  the  current  of  force,  by  its  attractive  power  will  indicate 
the  nature  of  cohesion.  The  magnetized  steel  has  a  circu- 
lating force,  which  will  leap  out  of  the  boundaries  of  the 
mass  to  bring  to  its  embrace  another  mass  of  iron  or  steel. 
Close  the  circuit  with  the  keeper,  and  the  force  revolves 
within,  as  the  bond  of  cohesion  between  the  keeper  and  the 
magnet,  and  not  only  so,  but  as  the  bond  of  cohesion  be- 
5 


50  OUTLINES   OF  A   SYSTEM   OF 

tween  the  atoms  of  the  magnet.  Thus  every  mass  has  its  cir- 
culating bond  of  force,  beyond  which  its  particles  may  not 
stray  ;  and  it  would  seem  as  if  nature,  having  no  fondness 
for  mystery,  hermetically  seals  up  none  of  her  processes, 
but  protrudes  the  force  of  cohesion  of  the  steel,  that  it  may 
be  perceived,  and  that  what  preserves  the  continuity  of  every 
mass  may  thus  be  known.  In  the  horseshoe  magnet  with  its 
keeper  the  current  of  force  circulates,  latent  and  unper- 
ceived  but  by  the  pendent  keeper  which  completes  the  orbit. 
In  the  circular  steel  the  force  is  just  as  active,  without  indi- 
cation except  by  the  general  cohesion  of  the  mass.  So  in 
the  bar  of  iron.  Thus  by  the  simple  law  of  nature  there 
is  continuity  of  mass,  oneness  from  multiplicity  ;  the  bond 
is  the  revolving  force.  Its  precise  manner  of  action  may  be 
traced  out. 

Science  as  yet  has  hardly  recognized  the  existence  of 
electricity  and  magnetism,  except  in  the  incidental  exhibitions 
of  their  power  in  the  magnetic  needle,  in  the  flash  of  the 
lightning,  in  the  artificial  spark  rubbed  from  the  glass  cylin- 
der in  the  lecture-room.  But  they  are  everywhere  a  mighty 
branch  of  the  great  stream  of  force  upholding  the  universe, 
connecting  together  the  creation  of  God. 

To  repeat  a  former  illustration,  would  you  ask  the  nature 
of  the  cement  of  the  brick  building,  which,  when  it  was 
torn  down,  filled  the  air  with  the  dust  of  lime  ?  Break  up 
the  cohesion  of  the  mass,  and  heat  is  evolved ;  —  can  you  then 
separate  heat  in  your  mind  as  something  opposite  to,  and  dis- 
tinct from  the  electrical  force  ?  Rub  substances  together, 
electricity  starts  forth  ;  —  does  not  electricity  then  circulate 
to  the  very  surface  of  the  mass,  and  often  beyond  the  mass  ? 

Pressure  is  therefore  the  connection  of  foreign  bodies  in 
near  contact,  by  the  force  of  cohesion  extending  itself  from 


MECHANICAL    PHILOSOPHY.  51 

mass  to  mass.  The  phenomena  of  friction  abundantly 
prove  this.  First,  because,  though  friction  bears  a  general 
ratio  to  the  quantity  of  matter  rubbed  together,  it  is  not  an 
invariable  quantity,  as  it  would  be  if  it  depended  solely  on 
the  weight  of  the  mass.  But  the  subject  must  be  examined 
in  its  details. 

Friction,  or  the  degree  of  friction,  if  it  were  induced  by 
weight  or  gravitation,  would  be  almost,  if  not  altogether,  an- 
nihilated in  a  smooth  body  moving  horizontally  on  another 
smooth  body,  which  is  not  the  case.  If  the  degree  of  fric- 
tion were  caused  by  weight,  it  would  be  a  constant  value, 
measurable  by  the  weight,  which  is  not  the  case.  If  the 
degree  of  friction  depended  on  smoothness  of  surface,  it 
would  be  measured  by  the  polish,  which  is  not  the  case.  If 
the  phenomena  of  friction  arise  mainly  from  the  passage  of 
electricity  between  the  rubbing  bodies,  it  will  have  a  gen- 
eral relation  to  the  extent  of  the  masses  ;  it  will  be  variable 
in  degree  ;  it  will  be  increased  or  diminished  according  to 
the  electric  nature  of  the  substances ;  it  will  be  increased  by 
the  presence  between  the  rubbing  substances  of  conducting 
bodies,  and  decreased  by  the  presence  of  non-conducting 
bodies  ;  it  will  be  increased  by  the  rubbing  together  those 
substances  inducing  magnetical  or  electrical  action,  and  the 
converse,  —  all  which  are  settled  facts. 

Thus  M.  Colomb  has  determined  by  experiment  that 
friction  is  increased  between  bodies  of  the  same  weight  and 
the  same  smoothness,  by  the  act  of  rubbing  together, — by  the 
gradual  induction  of  the  electrical  force.  Bodies  of  differ- 
ent structure  obtain  their  maximum  of  pressure  in  differ- 
ent times.  For  one  instance,  a  weight  of  one  thousand  six 
hundred  and  fifty  pounds  in  contact  was  moved  at  first  with 
a  force  measured  by  sixty-four  pounds  ;  in  the  lapse  of  three 


52  OUTLINES    OP   A   SYSTEM   OF 

seconds,  it  required  a  force  of  one  hundred  pounds  ;  in 
three  days,  six  hundred  and  twenty-five  pounds  would 
hardly  move  it. 

Again ;  to  create  the  electrical  state  it  is  not  necessary  that 
the  bodies  should  be  rubbed  together,  it  being  induced  at 
times  by  contact  merely.  The  iron  wheel  of  the  locomotive 
only  touches  the  track,  bears  upon  it,  and  is  lifted.  If  there 
were  no  rnagnetical  action,  the  wheel  would  turn  at  the 
axle,  but  not  impel  the  train.  Yet  the  circumference  of  the 
wheel  must  adhere,  for  propulsion.  If  the  non-conducting 
substance,  ice  or  snow,  is  on  the  track,  then  this  electrical 
action  is  so  much  reduced  that  the  pressure  is  not  sufficient 
to  turn  the  wheel ;  or  rather  the  wheel  turns  by  the  con- 
ducting rod,  but  for  the  want  of  electrical  action,  pressure, 
friction,  weight,  —  call  it  what  you  will, — it  takes  no  hold 
upon  the  track,  and  the  locomotive  cannot  advance.  A  prac- 
tical engineer  in  conversation  indicated  his  knowledge  of  the 
fact,  that  the  passage  of  the  train  over  the  track  induces 
magnetical  action.  Pointing  to  a  pile  of  unused  railroad 
bars,  he  said,  "  Those  bars  have  been  exposed  to  the  air  a 
few  days  only,  and  they  are  red  with  rust,  while  the  bars 
laid  down  for  years  in  constant  use  scarcely  show  rust.  Is  it 
not,"  asked  he,  "  the  effect  of  magnetism  ?  "  When  we  ride 
swiftly  over  the  winter  railroad, — the  snow,  —  one  is  apt  to 
think  of  the  smoothness  of  the  snow  only  as  decreasing  the 
friction  of  the  runners  of  the  sleigh,  forgetting  that  ice  is  a 
non-conductor  of  that  which  determines  friction. 

Of  course,  when  we  speak  of  friction,  we  know  that  it  is 
modified  by  smoothness  of  surface,  —  that  rough  surfaces 
cannot  be  rubbed  together  without  force  to  break  up  the 
cohesion  of  the  projecting  points ;  but,  aside  from  this 
with  equal  polish,  the  extent  of  pressure  is  measured  by  the 


MECHANICAL  PHILOSOPHY.  53 

passage  between  the  surfaces  of  the  electric  or  magnetic 
force.  Thus  of  iron  rubbing  on  iron  the  pressure  may  be 
indicated  by  the  fraction  f,  while  iron  rubbing  on  copper, 
with  no  smoother  surface,  stands  at  ^  ;  for  the  reason  that 
iron  and  iron  excite  the  more  intense  magnetical  action. 

The  effect  of  oil  as  a  non-conductor,  decreasing  pressure 
and  friction,  is  perfectly  indicative  of  what  constitutes  pres- 
sure and  friction  ;  and  so  is  the  converse  practical  act :  if 
we  wish  to  walk  securely  on  ice,  we  must  excite  electrical 
action,  put  on  the  woollen  moccasins  ;  "  coarse  woollen  and 
glass  or  ice  excite  the  electric  action."  Thus  empirically 
do  mechanics  excite  or  repress  friction,  often  without 
the  least  reference  to  principle.  Oil  and  ice  are  smooth, 
slippery,  &c.  Why  slippery,  has  not  been  indicated.  In 
the  manufacturing  of  plate  glass,  two  plates  placed  with 
their  surfaces  in  contact,  are  sometimes  found  to  adhere 
with  such  strength  of  cohesion  at  the  former  surface  of 
separation,  that,  in  the  act  of  separating  them,  the  split  is 
not  coincident  with  the  line  of  junction.  Oil,  or  any  other 
non-conducting  substance,  would  prevent  this  formation  of 
cohesion  between  them.  We  have  the  following  facts  from 
one  practically  well  acquainted  with  machinery.  A  piece  of 
smooth  cast  iron  revolving  on  other  cast  iron,  without  oil, 
will  often  file  away  the  iron  on  which  it  revolves  with  great 
rapidity,  the  iron  dust  falling  as  saw-dust  from  the  sawed 
wood.  A  revolving  spindle?  or  other  wrought  iron  body, 
moving  on  a  wrought  iron  axis,  without  oil,  will  often  increase 
its  friction  until  the  motion  is  stopped  by  it,  and  the  two 
pieces  of  iron  will  be  found  cemented  or  welded  together, 
so  as  not  to  come  apart  at  the  former  surfaces,  and  when 
separated  the  grain  of  the  iron  is  broken.  "  I  have  been 
told,"  said  he,  "  of  mills  being  stopped  by  this  adhesion  of  the 

5* 


54  OUTLINES   OF   A   SYSTEM   OF 

gudgeon  of  the  propelling  wheel  for  the  want  of  oil."  Other 
instances  will  occur  to  every  one,  such  as  the  close  adhe- 
sion of  two  pieces  of  glass  when  wet,  their  slight  adhesion 
when  greased ;  the  two  drops  of  water  kept  from  union  by 
a  thin  coating  of  dust ;  the  stratum  of  oil  over  water  pre- 
venting the  water  from  freezing,  though  cooled  below  the 
point  of  congelation  ;  air  prevented  from  penetrating  the 
wire  gauze  when  wet ;  the  non-ascent  of  water  in  capil- 
lary tubes  composed  of  a  material  that  cannot  be  wetted  ; 
the  spreading  of  oil  in  woollen  cloth  ;  the  repulsion,  as  it  were, 
of  oil  and  water  ;  the  rise  of  water  in  the  pores  of  a  lump 
of  sugar ;  the  process  of  the  solution  of  the  sugar.  In  fine, 
the  whole  class  of  phenomena  of  what  is  called  homogeneous 
and  heterogeneous  attraction,  is  traceable  to  this  principle, 
the  extending,  imparting,  diminishing,  taking  away  the 
bonds  of  cohesion  by  the  presence  of  body  with  body, 
according  to  their  electric  and  dielectric  natures. 

We  read  in  old  philosophy,  "  that  flat  and  smooth  sur- 
faces of  metals,  glass,  &c.  do  also  adhere  with  considerable 
force,  but  with  some  other  bodies  a  certain  artifice  is  required 
for  the  purpose,  namely,  the  interposition  of  some  fluid,  as 
oil  or  water,  &c.,  or  of  some  substance  that  may  be  applied 
in  a  soft  state,  which  will  after  coagulate  and  grow  solid,  as 
tallow,  wax,  and  fluid  metals.  Where  something  is  inter- 
posed, the  cementing  or  adhesion  seems  not  to  take  place 
between  the  two  surfaces,  but  between  each  of  those  sur- 
faces and  the  interposed  substance  ;  for,  in  the  first  place, 
it  seems  strange  that  the  surfaces  should  have  a  greater 
attraction  when  something  is  interposed  than  otherwise  ;  and 
secondly,  it  has  been  found  that  the  adhesion  differs  accord- 
ing to  the  different  substance  inserted  between." 

Hence  adhesion  is  not  the  attraction  of  the  adhering  sub- 


MECHANICAL  PHILOSOPHY.  55 

stances.  The  artifice  of  cements  is  the  interposition  of  some 
substance,  the  electrical  nature  of  which  is  such  as  to  per- 
mit the  force  of  cohesion  of  the  two  masses  to  pass  and 
circulate  through  both  ;  it  is  the  enlargement  of  the  orbit  of 
the  circulating  force  ;  it  is  making  common  orbits  from 
special  orbits  ;  it  is  extending  the  bond  of  continuity.  The 
act  of  soldering  is  an  instance  of  this  process  most  perfectly 
accomplished,  as  the  interposed  substance  is  of  the  same 
structure  and  elementary  constitution  with  those  united. 
We  notice  also  the  converse  in  the  amalgams  which  mer- 
cury forms  with  other  metals  ;  the  mercury  becoming  to  a 
degree  solidified,  the  other  metal  to  a  degree  made  fluid, 
so  as  to  produce  the  mean  of  the  cohesive  force  of  the 
mingled  metals. 

There  is  also  a  modification  of  the  force  of  cohesion  by  the 
mechanical  addition  of  force.  Let  a  heavy  weight  be  sus- 
pended by  a  copper  wire,  the  wire  will  remain  of  the  same 
length ;  but  by  striking  the  suspended  weight  so  as  to  give  a 
vibratory  motion  to  the  particles  of  copper  composing  the 
wire,  the  wire  will  become  longer  ;  —  there  is  added  force, 
greater  molecular  motion,  wider  orbits,  and  of  course  a 
lengthened  wire.  Crystals  form  in  a  saturated  solution  by 
the  addition  of  force  in  agitating  the  water.  Crystals  also 
are  formed  on  foreign  substances,  by  the  extension  of  the 
force  of  cohesion  from  the  bodies  on  which  they  form. 
Light,  which  is  a  form  of  force,  induces  crystallization. 

"When  one  substance  is  rubbed  upon  another,  the  body  in 
motion  preserves  its  own  force  of  cohesion,  and  breaks  up 
the  cohesion  of  the  body  at  rest  on  which  it  moves.  This 
fact  is  illustrated  by  the  tallow  candle  fired  from  the  gun, 
the  tallow  by  its  velocity  or  intense  present  force  preserving 
its  own  cohesion,  and  breaking  up  the  cohesion  of  a  far 


56  OUTLINES    OF   A    SYSTEM    OF 

harder  body;  — also  by  the  action  of  the  comparatively 
softer  grindstone,  in  its  revolution  wearing  away  the  harder 
steel ;  and  by  the  diluvial  striae,  which  are  grooves  worn 
into  the  surface  of  the  rock,  by  the  rapid  passage  of  an 
angle  of  a  rock  no  harder  than  itself. 

The  destruction  of  cohesion  by  the  act  of  cutting  with  a 
keen  instrument,  is  much  more  nearly  connected  with  elec- 
trical action  than  is  generally  supposed.  It  is  well  known 
that  the  electric  spark  will,  under  certain  conditions,  per- 
forate a  glass  jar  ;  its  perforation  of  the  pasteboard  card  is 
a  frequent  experiment.  Steel  has  high  magnetic  proper- 
ties ;  and  the  intensity  of  the  action  of  electrical  force  is 
increased  in  proportion  to  the  reduction  of  its  orbit  of  circu- 
lation. We  have,  then,  in  the  sharp  edge,  for  instance,  of 
the  razor,  the  condition  of  great  electrical  activity.  It  has 
often  been  remarked  that  the  keenness  of  the  edge  varies 
without  assignable  cause.  A  condemned  razor,  used  acci- 
dentally, will  sometimes  be  found  to  have  its  edge  restored 
by  lapse  of  time.  The  strapping  of  the  razor  is  usually  on 
non-conducting  substances ;  but  the  edge  is  often  restored 
by  strapping  on  metallic  surfaces.  Between  both  a  fine 
edge  can  be  obtained,  as  if  the  keenness  depended  on  one 
exact  degree  of  magnetical  induction.  Strapping  does  not 
wear  away  the  steel,  or  make  the  edge  thinner  ;  for  strap- 
ping on  the  palm  of  the  hand  will  often  be  effectual.  The 
nature  of  the  stroke  which  severs,  strengthens  the  opinion 
that  the  act  of  cutting  with  the  keen  edge  is  not  dependent 
on  force  to  break  cohesion,  but  on  the  electrical  induction. 
Thus  by  establishing  correct  theories  in  relation  to  actions 
of  an  enlarged  sphere,  even  trivial  operations  and  the  com- 
mon arts  may  be  improved. 

From  all  the  foregoing  we  are  led  to  believe  that  the 


MECHANICAL  PHILOSOPHY.  57 

circulation  of  force  is  the  bond  of  cohesion,  and  that  the 
acts  of  separating  and  of  connecting,  of  lubrication  and 
of  cement,  of  pressure  and  of  friction,  are  electrical  phe- 
nomena. 

To  Boerhaave  is  assigned  the  honor  of  originating  the  idea 
that  chemical  affinity  is  a  peculiar  force,  having  under  its 
control  the  elementary  particles  of  matter.  By  affinity  in 
this  use  of  the  word  is  meant  attraction.  The  word  affinity 
was  first  used  in  France,  to  avoid  the  word  attraction, 
"  which  had  the  taint  of  Newtonism."  Elective  affinity 
expresses  a  choice  of  matter  in  the  exercise  of  its  attractive 
power.  Berthollet  asserted  that  affinity  is  not  elective,  — — 
that,  when  various  elements  are  brought  together,  their 
combinations  do  not  depend  on  the  kind  of  element,  but 
upon  the  quantity  of  each  which  is  present,  that  which 
is  the  most  abundant  entering  most  largely  into  the  resulting 
compounds.  This  doctrine  was  assailed,  and  the  celebrated 
chemist  Berzelius  says,  "  Berthollet  defended  himself  with 
great  acuteness,  which  makes  the  reader  hesitate,  but  the 
great  mass  of  facts  finally  decided  the  point  against  him." 
The  theory  of  Dalton.  at  present  the  accepted  theory,  rests 
upon  the  idea  of  substance  as  well  as  upon  that  of  choice  by 
the  attracting  power. 

If  we  affix  the  usual  meaning  to  the  words  choice,  prefer- 
ence, election,  the  idea  is  very  unphilosophical.  If  the 
words  be  retained  in  chemical  science,  they  must  be  under- 
stood as  conveying  no  other  meaning,  than  that  chemical 
action  is  determined  by  the  laws  of  force,  which  destroy 
and  rebuild  the  structure  of  masses.  The  laws  of  force 
never  vary  ;  their  seeming  changes  in  relation  to  the  move- 
ments of  particles  come  from  defective  observation,  and 
reason  must  supply  the  deficiency  of  perception.  We  must 


58  OUTLINES   OF  A   SYSTEM   OF 

interpret  the  minute  by  knowledge  gained  from  the  ex- 
tended. Thus,  water  and  oil  will  not  chemically  unite. 
Why  ?  The  action  of  oil  in  preventing  the  union  of  iron 
with  iron  is  from  its  dielectric  properties.  It  is  an  electrical 
phenomenon.  So  water  and  oil,  from  their  opposite  elec- 
trical natures,  from  the  want  of  force  equally  and  commonly 
diffused,  will  not  unite  chemically.  We  cannot  form  one 
mass  or  volume  from  the  two.  Add  an  alkali,  and  the 
union  of  the  three  substances  is  formed.  What  analogical 
action  is  there  in  the  extended  ?  Does  not  non-conduct- 
ing matter  separate  bodies  or  repress  friction  ?  Is  not 
the  action  of  cements  founded  on  the  relations  of  the  vary- 
ing capacities  for  force  ?  We  shall  again  advert  to  the 
subject,  perhaps  better  prepared  to  entertain  the  position, 
that  the  law  which  determines  union  is  the  capacity  of  the 
bodies  present  equally  to  diffuse  the  force  of  cohesion,  and 
the  more  intimate  bond  of  connection.  Chemical  union  is 
of  the  same  nature,  the  one  mingling  the  elements,  the  other 
mingling  the  particles ;  the  one  determining  the  chemical 
nature,  the  other  determining  the  mass  of  aggregation  ;  the 
one  effected  by  the  force  of  cohesion,  the  other  by  the  force 
of  constitution.  Both  are  of  the  same  nature,  and  under 
the  action  of  the  same  laws. 

It  may  be  objected  to  this  view  that  the  generalization 
is  too  far  extended.  But  we  can  hardly  err  on  this  side. 
The  present  state  of  philosophy  seems  to  demand  generali- 
zation, —  the  grouping  together  of  the  heretofore  isolated 
action  of  nature.  Nature  has  been  too  much  parcelled  out, 
—  too  much  separated  into  artificial  departments.  There 
have  been  too  many  tribunals  set  up,  each  with  its  own 
code  of  laws.  Such  divisions  are  not  characteristic  of 
the  simplicity  of  truth ;  but  have  been  made  from  the 


MECHANICAL    PHILOSOPHY.  59 

necessity  of  the  case.  There  is  an  error  in  the  theory 
which  relates  to  general  principles.  Gravitation  cannot  be 
brought  down  to  the  particulars ;  it  will  not  apply  to  the 
minute.  It  has  to  be  added  to,  or  taken  from  ;  it  has  to  be 
modified  for  every  class  of  phenomena.  Thus  have  we  grav- 
itation, attraction,  elective  attraction,  capillary  attraction, 
attraction  of  cohesion,  attraction  dynamic,  attraction  statical, 
attraction  between  elements  of  one  kind,  attraction  be- 
tween masses  of  different  kinds,  and  so  on,  almost  without 
end  ;  and  in  place  of  science  giving  method  to  the  mind, 
clearness  and  distinctness  to  thought,  the  intellect  is  embar- 
rassed in  its  attempts  to  assign  to  nature  the  modicum  of 
order  which  the  theory  itself  may  have  in  minds  of  the 
greatest  strength. 


<"'.!  **' 


CHAPTER  IV. 

"  TVE  ARE  NOT  TO  ADMIT  OTHER  CAUSES  OF  NATURAL  THINGS  THAN 
SUCH  AS  ARE  BOTH  TRUE,  AND  SUFFICE  FOR  THE  EXPLANATION 
OF  THEIR  PHENOMENA."  —  NewtOH. 

THE  third  law  of  motion  is  usually  expressed  in  these 
words :  "  Action  and  reaction  are  equal,  and  in  contrary 
directions  ;  that  is,  equal  and  contrary  changes  are  pro- 
duced on  bodies  which  mutually  act  on  each  other." 

Sir  Isaac  Newton  seemed  to  consider  the  equality  of 
action  and  reaction  in  the  light  of  an  axiom  deduced  from 
the  relation  of  ideas,  rather  than  an  idea  induced  from 
the  observed  relations  of  things,  —  to  be  believed  by  a 
law  of  the  mind  rather  than  from  observation  of  phenomena. 
From  this  law  of  the  mind,  "  he  presumed,  because  the  sun 
attracted  the  planets,  those  also  attracted  the  sun  ;  and  he 
is  at  much  pains  to  point  out  to  astronomers,  the  phenomena 
by  which  this  may  be  proved  when  the  art  of  observation 
shall  be  sufficiently  perfected."  But  Mr.  Robison,  in  his 
Elements  of  Mechanical  Philosophy,  considers  this  doubt- 
ful, and  says  that,  because  a  magnet  causes  the  iron  to 
approach  towards  it,  it  does  not  appear  that  from  a  law  of 
the  mind  we  are  led  to  the  belief  that  iron  also  attracts  the 
magnet.  He  therefore  states  it  as  a  fact  with  respect  to 
all  bodies  "  on  which  we  can  make  experiment  or  observa- 
tion fit  for  deciding  the  question."  Maclaurin  does  not 
consider  it  as  deducible  a  priori  from  abstract  considera- 


MECHANICAL    PHILOSOPHY.  61 

tions,  but  thinks  of  it  as  the  effect  of  an  arbitrary  arrange- 
ment. Mr.  Stewart  says  that  it  is  "  more  safe  and  more 
logical  to  consider  it  as  an  experimental  truth,  without  ven- 
turing to  decide  on  either  side  of  the  question."  The  origin 
of  the  idea  we  trace,  however,  neither  to  the  relations  of 
ideas,  nor  to  the  relations  of  things,  but  to  the  action  of  the 
human  body  in  the  exertion  of  its  muscular  power.  When 
we  attempt  to  move  a  heavy  mass,  there  is  a  feeling  as  if  it 
withstood  the  strength,  reacting  as  it  were  against  the  effort 
put  forth.  This  is  probably  the  origin  of  the  idea,  and  it 
serves  in  almost  every  treatise  on  the  subject  as  an  illustra- 
tion of  the  law. 

The  observed  facts  which  give  support  to  the  law  are  all 
such  as  manifest  the  continued  action  of  the  same  force, 
with  its  induced  motion  changed  in  direction ;  —  as  in 
the  impingement  of  billiard  balls;  —  in  the  resistance  of 
water  to  the  motion  of  a  ship ;  —  in  the  counterpoise  of 
two  heavy  bodies,  where  one  descends  with  the  same  quan- 
tity of  motion  with  which  the  other  ascends; — in  the 
vibration  of  the  pendulum,  the  rise  being  equal  to  the 
fall ;  —  in  the  rebound  of  a  ball  in  proportion  to  the 
strength  of  the  impulse  given.  The  law,  therefore,  as  it 
stands,  affirms  with  some  obscurity  the  doctrine  of  the  inde- 
pendent existence  of  force,  of  its  transfer  to  other  bodies  in 
whole  or  in  part,  and  of  the  change  of  direction  often  in- 
duced if  it  continue  in  the  same  body.  In  this  point  of  view 
the  law  stands,  as  has  been  said,  as  the  basis  of  mechanical 
philosophy,  and  rightly  understood  expresses  a  universal  law 
which  applies  to  all  motion  in  the  universe  ;  —  Action  pro- 
ceeds from  force,  reaction  proceeds  from  the  same  force. 
The  result  of  any  degree  of  force  is  continued  action.  It 
may  be  divided,  giving  two  bodies  equal  and  contrary  action, 

6 


62  OUTLINES    OP   A   SYSTEM    OF 

or  it  may  continue  in  the  same  body  acting  in  a  contrary 
direction.  The  action  of  force  is  uniform  ;  its  transfer  and 
line  of  direction  contingent. 

There  is  an  unintelligibility  in  the  doctrine  of  reaction  as 
usually  explained.  It  is  very  difficult  of  statement  in  con- 
formity with  the  present  theories  of  motion  and  the  causes  of 
motion.  We  turn  to  a  philosophical  treatise  of  rather  ancient 
date,  and  find  these  instances  given :  "  When  a  man  strikes 
one  hand  against  the  other,  the  blow  is  felt  equally  by  both 
hands  ;  if  you  strike  a  glass  bottle  with  a  steel  hammer,  or 
the  hammer  with  the  bottle,  in  either  case  the  bottle  will  be 
broken  if  the  blow  be  sufficient ;  if  a  stone  be  tied  to  a  horse 
by  means  of  a  rope,  the  horse  in  dragging  the  stone  will 
exert  a  degree  of  force  equal  to  the  resistance  of  the  stone, 
for  the  rope  will  equally  pull  the  horse  toward  the  stone, 
and  the  stone  toward  the  horse."  But  then,  the  error  was 
too  palpable,  and  the  writer  destroys  the  law  at  once, 
adding,  "  and  in  fact  the  stone  will  not  follow  the  horse, 
unless  the  power  of  the  horse  be  greater  than  the  power  of 
the  stone."  Indeed,  there  could  be  no  motion  under  the 
law  as  usually  stated,  for  all  action  would  be  met  with  equal 
resistance.  It  is  however  sometimes  stated  in  such  a  man- 
ner as  to  give  the  idea  that  force  is  increased  by  being  com- 
municated. Dr.  Arnott,  in  his  Elements  of  Physics,  says, 
"  When  any  elastic  body,  as  a  billiard  ball,  strikes  another 
larger  than  itself  and  rebounds,  it  gives  to  that  other,  not 
only  all  the  motion  which  it  originally  possessed,  but  an  ad- 
ditional quantity,  equal  to  that  with  which  it  recoils,  owing 
to  the  equal  action  in  both  directions  of  the  repulsion  or 
spring  which  causes  the  recoil.  When  the  difference  of 
size  between  the  bodies  is  very  great,  the  returning  velocity 
of  the  smaller  is  nearly  as  great  as  its  advancing  motion  was, 


MECHANICAL   PHILOSOPHY.  63 

and  it  gives  a  momentum  to  the  body  struck,  nearly  double 
of  what  it  originally  itself  possessed.  This  phenomenon 
constitutes  the  paradoxical  case  of  an  effect  being  greater 
than  its  cause."  These  statements  must  always  be  under- 
stood in  conformity  with  the  principle,  that  every  degree  of 
force  gives  its  definite  amount  of  motion,  though  the  quan- 
tity of  motion  may  appear  different  from  acting  on  different 
quantities  of  matter. 

"We  will,  however,  state  the  doctrine  of  resistance  in  the 
words  of  Prof.  Daniell,  who  is  distinguished  for  accuracy  in 
the  enunciation  of  his  opinions.  He  says,  "  In  lifting  a  lump 
of  iron  or  lead  we  are  conscious  of  opposition,  and  conse- 
quent exertion."  Of  course  ;  for  the  application  of  strength 
animal  force  is  always  attended  by  effort,  by  exertion ;  the 
effort  is  not  because  the  iron  or  lead  resists,  but  because  to 
raise  it  requires  the  application  of  force  for  its  rotation  at 
the  higher  level.  He  continues,  —  "  In  drawing  a  bow,  we 
feel  an  opposing  resistance  which  we  denominate  elasticity, 
a  gradually  increasing  opposition  which  our  utmost  force 
may  not  be  able  to  overcome."  ..."  If  the  opposition  be  sud- 
denly withdrawn  and  the  bow  be  allowed  to  act,  on  its 
return  the  arrow  will  have  a  projectile  force  communicated 
to  it."  All  this  is  true.  The  muscles  of  the  arm  by  force 
separate  the  atoms  composing  the  one  side  of  the  bow,  and 
press  together  the  atoms  on  the  other  side  of  the  bow. 
When  the  action  of  the  muscles  ceases,  the  atoms  of  the  bow 
return  to  their  normal  position,  and  the  force  that  disturbed 
them  is  communicated  to  the  arrow,  which  rushes  forward, 
gradually  imparting  its  force  to  the  air,  till  exhausted  it  falls 
to  the  ground.  Here  there  is  no  reaction  whatever.  But 
we  find  in  this  instance  a  beautiful  analogy  between  the 
action  of  the  bow  and  of  the  bent  arm,  in  the  will  to 


64  OUTLINES    OF   A    SYSTEM   OF 

straighten  the  arm,  and  in  the  will  of  nature  to  straighten 
the  bow. 

The  idea  of  reaction,  as  we  have  said,  undoubtedly  came 
from  the  idea  of  resistance  in  the  exertion  of  muscular  force. 
We  cannot  with  the  hand  move  a  body  without  feeling  what 
is  called  reaction  ;  and  probably  the  best  instance  that  can 
be  given  is  the  result  of  the  action  of  standing  in  one  boat 
and  pushing  off  another  boat,  in  which  case  resistance  is  felt, 
and  the  reaction  gives  the  contrary  equal  backward  motion. 
But  it  is  most  readily  explained.  The  action  of  the  body  in 
this  case  is  like  that  of  a  bent  spring  with  one  end  in  each  boat, 
and  of  course  it  acts  equally  on  both  in  opposite  directions. 

The  author  just  referred  to  asks  this  question,  the  true 
solution  of  which  more  fully  explains  the  action  of  the  spring, 
though  his  answer  is  obscure  :  "  Is  a  spring  stretched  by 
the  sum  of  the  forces  of  the  two  arms,  or  by  one  only  ?  " 
This  is  his  reply :  "  Let  one  end  of  the  spring  be  attached 
to  a  fixed  support,  and  it  will  be  found  that  the  same  effort 
of  one  arm,  or  one  weight,  will  stretch  it  to  the  same  amount 
as  before  ;  the  force  of  the  other  arm  or  other  weight  only 
measured  the  resistance,  —  the  amount  of  reaction,  which 
necessarily  accompanies  the  action,  and  which  is  now  borne 
by  the  support. "  We  reply,  there  is  no  reaction  whatever ; 
the  needed  force,  whether  from  weight,  from  one  arm,  or 
from  two  arms,  is  supplied.  A  given  degree,  a  measurable, 
determinate  quantity  of  force  must  be  applied  whenever  and 
however  the  spring  be  bent ;  but  this  force  must  be  either 
applied  to  both  ends,  or  one  end  must  be  secured  and  all  the 
force  applied  to  the  other  end.  These  are  the  conditions 
on  which  the  spring  is  bent,  or  on  which  the  force  is  applied 
to  the  atoms  of  the  spring  ;  without  these  conditions,  if  force 
be  applied  it  will  move  the  spring  upward,  downward,  or 


MECHANICAL    PHILOSOPHY.  65 

sidewise,  as  a  whole.  Here  "resistance"  is  the  condition 
on  which  the  spring  can  be  bent.  The  strings  of  the  harp 
on  the  application  of  force  can  be  moved  without  being 
strung  upon  the  instrument,  but  their  melody  of  vibration 
comes  from  their  tension.  The  arm  not  "  resisted  "  at  the 
shoulder  could  move  no  weight. 

It  is  said  that  the  blow  of  a  hammer  on  an  anvil  is  accom- 
panied by  reaction.  We  answer, — A  part  of  the  force  which 
gives  the  blow  is  not  transferred,  but  relifts  the  hammer, 
and,  if  the  blow  be  unskilfully  given,  will  declare  its  presence 
by  a  sharp  vibration  in  the  hand  which  holds  it ;  a  part  is 
transferred  to  the  anvil  which  vibrates  the  anvil,  and  the 
force  spreading  in  all  directions  vibrates  the  air  with  a 
ringing  sound.  Let,  however,  the  blow  of  the  hammer  fall 
upon  heated  iron,  then  the  hammer  is  not  relifted,  and 
the  force  is  mainly  transferred  to  the  iron,  a  small  portion 
only  escaping,  giving  a  heavy  vibration  to  the  air.  A  most 
striking  illustration  of  the  distinction  between  absorbed 
force  and  transferred  force  is  this :  —  If  a  string  be  pulled  with 
great  force  and  it  breaks,  "reaction"  will  cause  him  who 
pulls  it  to  fall,  —  the  unused  force  returns  ;  let  him  draw 
wire  through  a  wire  plate,  expending  the  same  force, — when 
the  end  slips  through  the  plate,  he  will  feel  no  reaction,  no 
shock,  but  will  stand  firm,  because  the  force  is  safely  deposit- 
ed among  the  particles  of  the  extended  iron.  We  remember 
repeating  the  experiment  with  wonder  at  the  different 
results,  —  the  very  results  which  might  have  been  affirmed 
without  the  test  of  experiment,  had  we  understood  the  laws 
of  force. 

The  motion  of  a  steamboat  is  generally  considered  as 
depending  on  reaction.  The  paddles  of  the  boat  strike  the 
water,  by  the  reaction  of  which,  it  is  said,  the  boat  is  pro- 

6* 


66  OUTLINES   OF  A   SYSTEM   OF 

pelled.  In  fact  the  common  statements  with  regard  to 
reaction  and  resistance  have  thrown  obscurity  over  the 
subject.  We  will  trace  out  the  action  of  the  wheel  of  the 
steamer,  in  the  hope  that  we  shall  find  the  truth,  and  the 
truth  in  this  one  instance  will  cover  the  whole  ground. 

It  is  the  force  of  the  steam  which  by  proper  mechan- 
ical appliances  causes  the  wheel  to  revolve.  If  the  wheel 
turned  in  a  vacuum,  all  the  force  of  the  steam  would  be  lost 
for  propulsion,  exhausting  itself  in  whirling  the  wheel ;  —  if 
the  paddles  revolved  against  an  immovable  body,  like  a 
ledge  of  granite,  all  the  force  of  the  steam  would  give  pro- 
pulsion to  the  boat ;  —  if  the  wheel  revolve  in  water,  a  part 
of  the  force  will  give  a  backward  motion  to  the  water,  and 
the  residue  will  give  propulsion  to  the  boat.  In  neither 
case  does  reaction  move  the  boat,  but  the  force  of  the 
steam ;  for  the  solid  granite  stands  firm  without  force  or 
motion,  and  of  the  water,  neither  the  portion  which  is 
unmoved,  nor  the  portion  which  moves  backward,  has  the 
least  effect  in  communicating  onward  motion  to  the  boat. 
It  might  as  well  be  said  that  the  water  at  the  bows  propels 
the  vessel  by  its  resistance,  as  that  the  water  at  the  wheel 
does  ;  or  that  the  iron  track  of  the  railroad  gives  propulsion 
to  the  locomotive,  as  that  the  track  of  the  wheel  in  the 
water  moves  the  boat.  The  force  which  impels  the  boat  is 
from  the  expansion  of  steam,  the  water  only  giving  direction 
to  the  motion  of  this  force. 

The  force  of  the  steam  as  generated  is  expansive,  acting 
in  every  direction  ;  it  could  be  let  off  safely  through  the 
pipes  into  the  air,  thus  wasting  its  strength,  or  it  could  be 
made  to  act  on  any  part  of  the  vessel,  breaking  her  into 
pieces.  To  be  useful  in  propelling  the  boat,  it  ntust  have 
one  line  of  direction  given  to  it.  This  direction  is  relative 


MECHANICAL    PHILOSOPHY.  67 

to  the  earth.  It  must,  therefore,  in  propulsion,  have  refer- 
ence to  something  external,  otherwise  the  "  two  ends  of  the 
spring"  would  act  in  the  ship,  giving  to  its  parts  motion  in 
opposite  directions  ;  to  give  to  the  boat  a  motion  relative 
to  the  earth,  one  end  must  be  acting  on  matter  outside  of  the 
boat.  The  action  of  the  wheel  on  immovable  granite  is 
the  securing  of  one  end  of  the  spring,  so  that  its  whole 
force  may  act  in  giving  motion  to  the  boat  with  the  other 
end  ;  and,  as  we  observed,  if  the  wheel  revolved  against  an 
immovable  body,  the  whole  force  would  be  used  for  propul- 
sion. Acting  against  water,  so  far  as  the  water  is  moved, 
the  force  is  lost ;  so  far  as  it  is  unmoved,  or  resists  being  put 
in  motion,  the  force  of  steam  is  of  use  for  propulsion. 
A  familiar  illustration  of  this  is,  that  in  rowing  a  boat  near 
the  shore,  if  the  oar  touches  the  rocks,  much  more  force 
adheres  to  the  boat  shooting  her  ahead,  since  none  of  the 
oarsman's  strength  is  wasted  in  giving  motion  to  the  water. 

If  we  place  the  hand  in  water,  moving  it  slowly,  a  slight 
resistance  will  be  felt,  and  the  resistance  will  increase  in  pro- 
portion to  the  velocity  of  the  motion  of  the  hand.  It  is  said 
that  a  ball  of  iron  will  strike  the  water  more  forcibly  than  a 
ball  of  cork  of  the  same  size,  and  be  more  resisted  than  the 
cork,  though  both  move  towards  the  water  with  the  same  ve- 
locity. Therefore  it  is  inferred  that  reaction  is  in  propor- 
tion to  momentum,  momentum  being  the  product  of  the 
velocity  by  the  weight. 

It  is  not  so.  The  resistance  to  a  body  impinging  the 
water  is  in  proportion,  not  to  its  momentum,  but  to  the 
quantity  of  the  water  to  be  moved  out  of  the  way,  and  the 
velocity  with  which  it  is  to  be  moved  away.  A  short  ship, 
say  fifty  feet  in  length,  with  a  momentum  represented  by 
100,  sails  five  miles  an  hour,  and  a  ship  one  hundred  feet 


68  OUTLINES    OF   A    SYSTEM    OF 

in  length  moves,  with  the  same  breeze  and  proportional 
canvas,  with  a  momentum  of  200.  The  resistance  increas- 
ing with  the  momentum,  with  the  same  force  in  proportion  to 
the  mass,  the  long  ship  under  the  theory  would  sail  only  five 
miles  an  hour.  Practically,  however,  the  longer  the  ship 
driven  by  the  same  proportional  force,  the  greater  the 
velocity ;  for  the  short  ship  with  the  momentum  100,  loses 
say  10  of  her  force  in  moving  away  the  water  from  her 
bows,  in  other  words,  in  opening  her  path.  In  the  long  ship, 
moved  with  the  momentum  200,  it  still  requires  only  10 
for  this  purpose,  leaving  190  for  propulsion,  which  is  95 
for  each  of  the  two  halves.  The  long  ship  has  then  -fa  more 
force  for  propulsion.  The  per  centage  of  force  needed  to 
open  the  path  is  less  in  the  long  than  in  the  short  ship. 

Thus  resistance  to  the  vessel  is  not  measured  by  the 
"  momentum  "  of  the  vessel,  but  by  the  quantity  of  water  to 
be  moved,  and  the  speed  with  which  it  is  moved  away. 
There  is,  in  fact,  no  resistance  in  the  case  whatever ;  but  a 
part  of  the  force  of  propulsion  is  necessarily  used  in  removing 
the  water  from  the  track.  There  are  other  circumstances 
which  modify  this  loss  of  force,  for  instance,  the  shape  of  the 
bows.  If  the  shape  be  such  that  the  water  is  elevated, 
there  is  a  loss  of  force  to  raise  this  water  above  the  level. 
The  form  of  the  ship  should  be  such  as  to  establish  a  current 
from  the  bows  to  the  stern.  The  less  the  surface  of  the 
water  is  disturbed,  the  better.  For  this  reason  a  body 
wholly  submerged  is  less  impeded  ;  for  the  path  opened  is 
but  a  circulation  of  the  water  from  one  end  to  the  other  of 
the  moving  body.  If  the  body  plunged  be  suddenly  moved 
under  water,  before  the  current  is  established,  the  water 
will  rise  in  a  wave  at  the  surface  ;  after  the  current  is  es- 
tablished by  the  moving  body,  the  surface  is  at  rest.  When 


MECHANICAL    PHILOSOPHY.  t>9 

the  wave    was  raised,  force  was  supplied  for  its  higher 
rotation. 

It  appears,  therefore,  that  what  is  called  the  resistance  of 
the  water  to  the  propelled  vessel,  comes  not  from  reaction, 
but  is  the  loss  of  force  in  establishing  the  current  by  which 
her  path  is  opened. 

In  the  preceding  statements  the  word  momentum  has  been 
employed  in  conformity  to  the  usual  language.  As  was  before 
observed,  momentum  is  the  degree  of  force  present  in  action 
upon  the  body.  It  is  the  energy  or  strength  of  the  motion. 
The  intensity  of  force  is  measurable  by  the  velocity  it  im- 
parts ;  but  as  it  requires  more  or  less  force  according  to  the 
weight  of  the  body,  to  move  a  body  with  a  given  velocity,  in 
ascertaining  the  present  force  of  a  body  in  motion,  its  weight 
is  one  of  the  elements  of  the  calculation.  Momentum  is 
therefore  the  force  which  moves  the  body,  —  that  which  it 
will  impart  when  the  motion  is  arrested.  It  is  simply  force, 
and  the  use  of  the  word  momentum  is  not  only  unnecessary, 
but  it  leads  to  a  confusion  of  ideas  to  employ  two  words  to 
express  the  same  thing. 

If  a  bullet  be  discharged  from  a  gun  through  a  door  left 
ajar,  it  will  pass  through  the  wood,  giving  no  motion  to  thOj 
door.  In  gunnery,  cannon  balls,  to  do  the  most  injury 
to  a  ship,  should  be  fired  with  small  charges  of  powder,  that 
they  may  not  pass  through  the  ship,  but  transfer  their  mo- 
tion to  it.  In  these  cases,  reaction  increases  with  the  les- 
sening of  the  force,  that  is,  if  the  ball  pass  through  the  ship, 
it  does  not  injure  the  ship  so  much  as  if  the  motion  of  the 
ball  be  arrested,  and  its  force  transferred  to  the  work  of 
destruction.  The  gun  recoils  proportionally  to  the  force 
of  the  explosion,  of  course  j  for  explosive  mixtures  act  in 
all  directions, 


70  OUTLINES    OF   A   SYSTEM    OF 

The  doctrine  of  vis  inertias  asks  a  passing  comment.  It 
is  inferred  from  the  first  law  of  motion.  Bodies  in  motion 
continue  in  motion  from  the  inertia  of  motion  ;  bodies  at 
rest  continue  at  rest  from  the  inertia  of  rest ;  that  is,  bodies 
which  move  do  move,  bodies  at  rest  are  at  rest.  This  is  all. 
The  idea  receives  some  coloring  from  two  facts.  First,  the 
progressive  motion  of  a  mass  is  in  proportion  to  the  force 
impressed,  and  takes  place  after  a  lapse  of  time  from  the 
application  of  the  force  to  the  atoms  of  the  body.  There 
is  needed  time  for  the  force  to  be  diffused  among  the  atoms 
by  atomic  motion,  before  consentaneous  or  progressive  motion 
is  induced.  The  other  fact  is,  that  in  most  cases  force  in 
moving  bodies  is  gradually  applied. 

Thus  a  bullet  slowly  moving  will  enter  the  water;  for 
it  can,  as  it  were,  await  the  tardy  resolution  of  the  atoms  of 
the  water  into  progressive  motion  to  give  it  place.  But  the 
bullet  from  the  gun  is  deflected.  Its  velocity  is  so  great 
that  it  cannot  transfer  its  force  ;  for  it  would  take  many 
instants  for  the  particles  of  water,  moving  with  the  same 
velocity  with  the  bullet,  to  travel  through  their  atomic  space, 
and  to  induce  progressive  motion  of  the  column  necessary 
io  be  moved  for  the  passage  of  the  bullet  through  the  water. 

We  now  come  to  the  consideration  of  another  principle, 
which  is  often  referred  to  in  the  explanation  of  the  mechan- 
ical powers.  It  is  this :  The  loss  of  time  is  the  gain  of 
power  ;  and,  conversely,  the  gain  of  time  is  the  loss  of 
power.  It  is  not  so.  Why,  let  us  ask,  are  there  in  the 
text-books  of  mechanical  philosophy  assertions  like  this  : 
"  Time  is  an  important  element  of  force  "  ?  Time  has  no 
reference  whatever  to  force,  or  to  motion  consequent  upon  the 
force  applied.  It  can  neither  make  nor  destroy  it.  It  can- 
not increase  or  diminish  it.  A  body  with  the  same  present 


MECHANICAL   PHILOSOPHY.  71 

force  moves  on  forever  with  an  uniform  motion.  Time  can 
never  change  the  quantity,  quality,  or  direction  of  motion. 
Time  is  a  succession  of  events.  It  is  itself  measured  by 
motion,  —  by  the  harmonic  uniform  motion  of  the  spheres. 
We  measure  motion  by  time  indirectly ;  its  direct  measure 
is  the  motion  of  the  earth.  Velocity  is  more  conveniently 
applied  to  the  artificial  divisions  of  time  than  to  the  earth's 
motion.  It  is,  perhaps,  better  for  common  purposes  to  say 
that  a  body  moves  so  many  miles  an  hour,  than  to  say  that 
it  moves  so  many  miles  while  the  earth  moves  one  twenty- 
fourth  of  a  rotation. 

But  the  doctrine  like  that  of  action  and  reaction,  and  of 
vis  inertioe,  has  a  coloring  or  semblance  of  truth  from  the 
misconception  of  facts.  In  two  ways  time  has  an  apparent 
connection  with  force,  as  if  time  increased  force. 

First ;  animal  or  muscular  force  is  produced  by  the  ani- 
mal by  a  succession  of  efforts.  It  is  generated  gradually, 
and  of  course  imparted  gradually.  By  time  the  force  is 
increased  or  added  to.  Time  does  not  increase  power ;  but 
the  muscles  can  supply  more  force  in  five  minutes  than  in 
one  minute.  This  idea  is  fully  illustrated  by  the  inclined 
plane.  A  horse,  in  dragging  up  a  weight,  has  more  time 
to  produce  the  required  force  ;  but  when  the  load  is  ele- 
vated, he  has  imparted  just  that  degree  of  force  which  is 
required  to  elevate  the  weight  directly,  at  once,  verti- 
cally. The  mechanical  power  of  the  inclined  plane  enables 
the  animal  to  do  by  successive  efforts  what  he  could 
not  do  at  once.  He  cannot  raise  the  weight  at  once  ;  he 
can  raise  the  weight  in  time.  A  man  cannot  raise  by  one 
effort  a  ton  of  iron  ten  feet,  but  in  an  hour  he  can  furnish 
the  necessary  force.  Yet,  it  is  said  in  a  work  on  mechanics, 
that  it  requires  no  force  to  move  a  body  horizontally,  full 


72  OUTLINES    OF   A    SYSTEM    OF 

force  to  raise  it  vertically,  and  that  the  gain  of  power  by  the 
inclined  plane  is  in  simple  proportion  to  the  angle  it  makes 
with  the  horizon ! 

Secondly  ;  another  misconception  is  of  the  law  of  falling 
bodies.  The  force  of  the  falling  stone,  it  is  commonly  said, 
increases  according  to  the  square  of  the  time  of  descent. 
The  force  increases  not  with  time,  but  with  every  line  of 
descent.  The  descending  body  has,  proportionally  to  its 
change  of  level,  an  increase  of  spare  force,  —  of  force 
unused  at  its  lower  level  of  rotation.  The  greater  the  fall, 
the  more  the  force. 

Thus  in  the  use  of  animal  strength,  and  in  the  use  of  the 
force  of  the  falling  body  there  is,  not  an  increase  of  force  by 
time,  but  an  addition  to  the  force  received  in  time.  A 
man's  power  of  labor  is  measured  by  time  ;  the  power  of  the 
waterfall  is  measured  by  the  space  of  descent,  or  for  con- 
venience' sake,  by  the  time  it  falls,  as  the  space  and  time 
are  in  one  fixed  ratio. 

So  simple  is  the  explanation  of  the  philosophy  of  the  me- 
chanical powers,  that  it  is  surprising  that  the  subject  should 
ever  have  been  deemed  intricate,  or  that  so  much  mathe- 
matical labor  should  have  been  wasted  on  it.  To  under- 
stand the  lever,  —  and,  that  understood,  all  the  mechanical 
powers  are  understood,  —  does  not  require  one  to  read 
Archimedes'  mathematical  demonstration,  nor  to  understand 
the  laws  of  statics,  dynamics,  virtual  velocities,  equilibrium 
of  forces,  and  centres  of  gravity.  Let  one  idea  be  present 
to  the  mind,  and  there  can  be  no  misconception.  The  force 
applied  is  the  force  that  produces  the  result ;  time  will  not 
increase  or  diminish  it,  it  ever  remains  of  one  intensity, 
capable  of  producing  only  one  degree  of  motion  ;  no  lapse  of 
time,  no  mechanical  skill  can  change  its  nature  or  degree. 


MECHANICAL  PHILOSOPHY.  73 

Without  reference  to  loss  by  friction,  it  may  be  transferred 
through  pulleys,  levers,  wheels,  over  inclined  planes,  when- 
ever needed,  and  when  used  at  the  end  of  the  line  there  is 
only,  and  just  that  force  which  was  at  first  applied.  It  will 
there  produce  the  same  quantity  of  motion,  neither  more 
nor  less,  that  its  direct  use  would  have  produced  without  the 
intervention  of  the  machinery.  If  by  the  lever  one  pound 
raises  two  pounds,  the  two  pounds  will  be  moved  half  as  far ; 
if  a  man  raise  a  ton  by  means  of  a  pully,  he  has  put  forth 
just  the  strength  that  would  be  required  to  raise  a  ton  to 
the  same  height  without  the  pully.  His  gain  has  been  the 
time  given  for  him  to  produce  and  apply  the  strength.  He 
could  not  lift  a  cord  of  wood  at  once,  but  log  by  log  he  can 
supply  the  needed  force  for  piling  it.  If  a  smaller  wheel . 
turn  a  larger  one  more  slowly,  there  is  still  the  same  degree 
of  motion  in  the  larger  wheel  that  was  in  the  smaller  ;  if 
the  larger  turn  the  smaller,  there  is  still  the  same  motion 
in  proportion  to  the  quantity  of  matter.  It  requires  one 
degree  of  force  to  give  one  quantity  of  motion  ;  a  given 
force  can  do  neither  more  nor  less.  This  is  rigorously  true, 
and,  if  it  be  understood,  there  is  no  mystery  about  the  me- 
chanical powers.  If  there  be  a  gain  of  power,  it  is  distinctly 
traceable  to  the  gradual  addition  of  force  from  animal 
strength,  or  from  the  increasing  force  of  a  descending  body. 
The  measurement  of  these  by  time  has  led  to  the  confusion 
thrown  over  the  subject  by  the  doctrine,  that  there  is  a  gain 
or  loss  of  force  by  time.  It  will  not  be  necessary  to  remark 
particularly  on  either  class  of  the  mechanical  powers,  as  it 
is  believed  that  this  general  statement  covers  the  whole 
ground. 

The  next  supposed  force  to  be  examined  is  the  centrifugal 
force,  or  the  tendency  of  bodies  moving  in  curved  lines  to 
7 


74  OUTLINES    OF    A    SYSTEM   OF 

assume  a  rectilinear  motion.  It  is  not  exactly  a  force, 
but  a  tendency  of  the  moving  mass  not  to  move  as  it  is 
moving.  In  the  Philosophy  of  the  Inductive  Sciences ,  we 
find  the  following  explanation  of  the  character  of  this  ten- 
dency. "  The  centrifugal  force  is  not  a  distinct  force  in  a 
strict  sense,  but  only  a  certain  result  of  the  first  law  of 
motion,  and  is  measured  by  the  portion  of  centripetal  force 
which  counteracts  it."  "  The  projectile  force  is  a  hypo- 
thetical impulse,  which  may  at  some  former  period  have 
caused  the  motion  to  begin,  while  the  central  force,  gravita- 
tion, is  an  actual  force  which  must  act  continuously,  and 
during  the  whole  time  of  motion,  in  order  that  the  motion 
may  go  on  in  the  curve." 

If  we  had  no  doubt  of  the  truth  of  the  theories  which 
relate  to  the  motions  of  the  spheres,  the  reading  of  such 
passages  would  suggest  a  doubt.  There  is  an  obscurity  of 
language,  not  arising  from  the  want  of  power  of  expression, 
for  no  man  has  more  power  than  this  author,  but  because 
there  was  no  distinct  idea  to  be  conveyed.  In  the  first  place, 
centrifugal  force  is  not  a  force,  but  a  result ;  not  being  a 
force,  it  is  still  measured  by  another  force.  Then,  the 
force  which  is  not  a  force  is  counteracted,  —  of  course  it  is 
destroyed,  it  no  longer  acts.  This  verbal  criticism  is  made 
only  for  the  argument,  that  doctrines  feebly  expressed  by 
strong  men  are  of  doubtful  soundness. 

It  is  supposed  that  the  moon,  for  instance,  received 
originally  an  impulse  of  motion  in  a  straight  line,  but  that, 
being  constantly  acted  upon  by  the  attraction  of  the  earth, 
the  straight  line  is  changed  into  the  curve  ;  that  the  attrac- 
tion of  the  earth  which  would,  unchecked,  draw  her  to  the 
earth,  is  opposed  by  the  centrifugal  force  ;  and  that  the 
moon,  under  the  influence  of  forces  acting  in  opposite  direc- 


MECHANICAL    PHILOSOPHY.  75 

tions,  is  held  in  her  orbitual  course,  the  original  impulse 
giving  the  motion. 

But  as  the  moon's  orbit  is  elliptical,  she  is  at  times  com- 
paratively nearer  to,  and  at  times  further  from  the  earth. 
Of  course,  in  her  changing  distance,  the  centripetal  and 
centrifugal  forces  vary  in  intensity.  The  earth  attracts 
less  or  more  according  to  distance,  and  the  counteracting 
force  changes  relatively  ;  they  preserve  an  equilibrium.  It 
cannot  be  that  the  force  of  opposition  can  remain  with  an 
equal  intensity,  when  the  force  of  attraction  is  continually 
changing.  They  therefore  change  proportionally,  or  to  the 
same  degree,  so  that  the  moon  is  guided  in  her  course  by 
forces  perfectly  elastic. 

Again  ;  if  the  original  impulse  of  the  moon's  motion  were 
an  impulse  of  rectilinear  motion,  and  the  attraction  of  the 
earth  acts  in  a  straight  line  to  her  centre,  how  from  two 
forces  acting  at  right  angles  is  the  curved  line  of  motion 
produced  ?  An  original  impulse  in  a  straight  line  of  direct- 
ion, and  another  impulse  in  a  straight  line  at  a  right  angle 
with  it,  would  ever  and  invariably  produce  a  straight  line  of 
motion  at  the  mean  distance,  half  way  between  the  two 
lines  of  impulse.  If  gravitation  changed  the  moon's  motion, 
the  moon  must  necessarily  be  brought  thereby  nearer  to  the 
earth  ;  if  it  act  on  the  moon  impelled  in  a  straight  line,  the 
resulting  motion  would  be  a  mean  direction,  lessening  the 
distance  between  the  attracting  and  attracted  bodies.  Even 
Newton,  at  an  early  period  of  his  speculations,  held  the 
opinion  that  the  result  of  attraction  on  the  impelling  force 
would  be  motion  in  a  kind  of  spiral. 

That  the  orbit  of  the  moon  could  be  formed  by  the  action 
of  the  two  forces,  has  been  nominally  proved  from  the  case 
of  the  cannon  ball,  which  under  the  joint  force  of  projection 


76  OUTLINES    OF   A    SYSTEM    OF 

and  gravitation  describes  a  curve.  But  the  case  is  not  an 
analogous  one.  The  curve  of  the  projectile  is  occasioned 
by  the  regular  decrease  of  the  force  of  impulse.  Its  onward 
force  is  gradually  lost  by  the  resistance  of  the  atmosphere, 
and  thus  "gravitation"  brings  the  path  described  into  a 
curve.  In  order  for  the  attraction  of  the  earth  to  give  a  curve 
to  the  orbit  of  the  moon,  the  impulse  of  the  moon  must  be 
gradually  lessened  by  some  retarding  medium,  as  the  can- 
non ball  is  retarded  by  its  passage  through  the  air,  whence 
would  result  a  spiral  curve  gradually  bringing  the  moon  to 
the  earth.  But  never  can  the  impulse  in  two  directions  of 
the  rectilinear  force  result  in  a  curve.  We  know  that  the  re- 
verse is  mathematically  proved,  and  that  the  nature  of  the 
curve  which  would  be  produced  is  pointed  out ;  but  the 
mathematics  by  which  this  is  done,  is  of  a  peculiar  kind 
introduced  with  the  theory  of  gravitation,  being  rendered 
necessary  by  this  theory. 

What  gives  the  elliptical  form  of  orbit,  —  for  instance,  of 
the  comet,  which,  at  one  time  widens  its  path  in  the  broad 
expanse  of  almost  limitless  space,  and  then  narrowing  its 
orbit,  almost  brushes  in  its  rapid  flight  the  face  of  the  sun  ? 
It  is  not  force  of  motion  ;  for  this  force  acts  according  to  the 
law  of  the  area  described  in  every  part  of  the  orbit.  It  is 
not  attraction  ;  for  attraction  merely  holds  its  own,  increas- 
ing or  diminishing  according  to  distance.  Nor  yet  is  it 
centrifugal  force  ;  for  this  follows,  and  is  measured  by,  gravi- 
tation. It  is  not  space  ;  for  there  is  no  grooved  channel  or 
marked  track  through  its  vastness.  A  sphere,  perfectly  a 
sphere,  each  atom  of  which  was  moved  with  equal  force, 
would  necessarily  describe  a  circle.  May  it  not  be  that  it 
is  the  shape  of  the  revolving  body ;  that,  if  the  shape  of  this 
world,  for  instance,  is  given,  the  ellipsis  of  her  orbit  may  be 


MECHANICAL    PHILOSOPHY.  77 

determined  ;  and  that,  if  we  knew  the  form  of  the  comet, 
its  eccentricity  of  path  could  be  understood. 

The  idea  of  centrifugal  force  grows  out  of  a  trivial,  and 
perhaps  misunderstood  fact,  and  is  invariably  illustrated  by 
it.  We  allude,  of  course,  to  the  action  of  the  sling.  From 
the  hand  proceeds  the  impulse  of  motion,  the  string  is  the 
gravitating  power,  or  that  which  by  its  tension  measures  this 
power,  and  the  tendency  of  the  stone  to  fly  off  in  a  tangent 
represents  the  centrifugal  force.  It  is  unquestionably  the 
tendency  of  the  stone  to  escape,  and,  if  the  string  were  to 
break  or  be  let  slip,  the  stone  would  no  longer  continue  to 
move  in  the  same  circle,  but  the  impressed  force  would  give 
it  another  direction  of  motion.  The  force  of  motion  of  the 
stone  is  from  the  centre.  There  is  nothing  to  give  the 
stone  its  circular  movement  except  the  string  ;  that  broken, 
the  impressed  force  gives  the  stone  a  curved  motion  in 
another  direction. 

So  far  is  this  action  from  being  analogous  to  the  motion 
of  the  nioon,  that  it  is  the  very  reverse.  The  stone  from 
the  sling  receives  force  acting  in  a  line  of  direction  from  the 
centre  ;  the  moon  receives  from  the  centre  of  her  orbit  an 
impulse  toward  the  centre.  It  is  not  a  fortunate  illustra- 
tion to  compare  the  effect  of  an  impulse  away  from  the 
centre,  to  an  impulse  affecting  the  body  and  drawing  it 
toward  the  centre. 

Centrifugal  force,  too,  is  often  illustrated  by  the  neces- 
sity which  a  man  finds  in  running  round  a  small  circle,  of 
leaning  inwards  toward  the  centre,  "to  counteract  the  cen- 
trifugal force."  But  we  will  quote  a  contrary  opinion : 
c<  Let  any  man  move  in  a  circular  or  elliptical  line  described 
or  marked  out  to  him,  and  he  will  find  no  tendency  in  him- 
self either  to  the  centre  or  from  the  centre.  If  he  attempt 

7* 


78  OUTLINES   OF  A   SYSTEM   OF 

the  motion  with  great  velocity,  or  if  he  do  it  carelessly  and 
inattentively,  he  may  go  out  of  the  line  either  from  the 
centre  or  towards  it ;  but  this  is  to  be  ascribed  not  to  the 
nature  of  the  motion  but  to  our  infirmity,  or  perhaps  to  the 
animal  form,  which  is  more  fitted  for  progressive  motion  in 
a  right  line  than  for  any  kind  of  curvilinear  motion." 
Thus  says  Lord  Monboddo,  and  proves  that  philosophers  are 
not  agreed  among  themselves  concerning  a  fact,  which  is 
assumed  as  a  "  standard  example  "  of  their  mechanical 
doctrines.  However  it  may  be  with  a  man  running  round 
in  a  circle,  we  feel  quite  sure  that  a  revolving  sphere  would 
not  have  to  lean  inward  to  prevent  its  falling  outward,  or  to 
lean  outward  to  prevent  its  falling  inward. 

The  action  of  the  governor  of  the  steam  engine  has  also 
been  referred  to,  in  order  to  illustrate  centrifugal  force. 
The  two  heavy  balls  are  so  suspended  that  when  not  revolv- 
ing they  hang  motionless  ;  endued  with  activity  in  propor- 
tion to  the  velocity  of  their  revolution,  they  rise,  and  describe 
wider  and  wider  revolutions.  The  reason  of  the  rise  of 
these  balls  is  the  force  communicated  to  them,  from  which 
they  take  a  higher  level  of  rotation,  —  a  beautiful  illustra- 
tion of  the  views  we  present.  They  could  not  thus  rise 
from  the  action  of  centrifugal  force,  were  there  any  centrifu- 
gal force  ;  it  impels,  if  it  impel  at  all,  from  the  centre. 

How  could  the  moon  be  held  in  her  orbit,  if  centrifugal 
force  acted  in  any*:other  direction  than  the  direction  oppo- 
site to  the  force  of  gravitation,  which  is  to  counteract  it  ? 

The  breaking  of  the  too  swiftly  revolving  wheel  is  another 
illustration  of  the  centrifugal  force,  which  keeps  the  planets 
from  responding  to  the  attraction  of  gravitation.  But  the 
application  of  force  to  turn  the  wheel  is  at  the  centre,  as 
in  the  sling  it  is  from  within  outward.  The  central  part 


MECHANICAL    PHILOSOPHY.  79 

of  the  wheel  as  truly  impels  the  circumference,  as  the 
crank  or  rod  impels  the  centre.  There  is  motion  induced 
under  the  condition,  that  the  cohesion  of  all  the  matter 
in  motion  will  bear  the  force  applied  at  the  centre.  If  too 
much  force  be  applied,  the  crank  or  the  wheel  may  break. 
The  greatest  force  required  is  at  the  circumference,  while 
the  force  is  applied  at  the  point  the  furthest  removed. 
Every  practical  mechanic  knows  that  there  is  no  danger  of 
a  wheel's  breaking  if  the  motive  force  be  applied  to  the  cir- 
cumference. But  nature  does  not  so  unskilfully  apply  her 
motive  power.  Her  force  for  revolution  or  rotation  is 
present  with  every  atom.  It  is  equally  diffused  through  the 
whole  mass,  every  particle  retaining  its  proportional  motive 
power  according  to  the  orbit  to  be  described  ;  each  moves 
of  itself,  and  from  its  own  energy  ;  one  does  not  push,  draw, 
or  impel  another.  There  is  for  this  reason  harmony  of 
motion,  all  things  moving  according  to  the  order  of  nature. 
Those  who  require  a  balance  of  forces,  conflicting  powers,  — 
those  who  compare  the  motion  of  the  spheres  to  a  school- 
boy's sling,  or  to  the  dizzying  whirl  of  a  man  running  in  a 
circle,  seem  to  degrade  the  mechanism  of  the  heavens  below 
the  results  of  human  ingenuity. 

We  pass  from  centrifugal  force  to  its  opposite,  centripetal 
or  attractive  force,  —  gravitation. 

It  may  be  well  to  give  an  outline  of  the  theory  as  pre- 
sented by  those  who  have  the  most  unshaken  confidence  in 
its  truth.  The  theory  of  universal  gravitation  asserts, 
that  the  force,  by  which  the  different  planets  are  attracted 
to  the  sun,  is  in  the  inverse  proportion  of  the  squares  of 
their  distances,  and  that  the  force,  by  which  the  same  planet 
is  attracted  to  the  sun  in  different  parts  of  its  orbit,  is  also 
in  the  inverse  proportion  of  the  squares  of  its  distances ; 


80  OUTLINES    OF   A   SYSTEM    OP 

that  the  earth  also  exerts  a  similar  force  on  the  moon,  and 
that  this  force  is  identical  with  the  force  of  gravity  ;  that 
bodies  thus  act  on  other  bodies  besides  those  which  revolve 
round  them  ;  that  thus  the  sun  exerts  such  a  force  on  the 
moon,  and  that  the  planets  exert  such  forces  on  one  another  ; 
further,  that  this  force,  thus  generally  exerted  by  the  entire 
masses  of  the  sun,  earth,  and  planets,  results  from  the 
attraction  of  each  particle  of  these  masses,  which  attraction 
follows  the  above  law,  and  belongs  to  all  matter  alike  ;  also, 
that  this  attraction,  operating  on  the  "  hypothetical  impulse 
of  motion,"  gives  its  spheroidal  form  to  the  earth,  and  their 
elliptical  form  to  the  orbits  of  the  heavenly  bodies. 

This  theory  has  been  a  settled  doctrine  of  philosophy  for 
nearly  two  centuries,  and  generally,  if  not  universally,  it  is 
deemed  an  established  truth.  It  seems  to  have  passed  away 
from  examination,  to  be  laid  aside  as  that  which  need  never 
again  be  the  subject  of  thought.  It  is  spoken  of  as  ascer- 
tained ;  and  its  discovery  and  extended  application  are 
considered  as  among  the  most  glorious  achievements  of  the 
human  intellect. 

Thus  it  will  be  almost  impossible,  even  if  the  theory  be 
not  founded  in  truth,  to  bring  the  minds  of  men  to  its  re- 
examination.  It  has  become  associated  with  the  universe 
from  its  most  enlarged  to  its  most  attenuated  parts.  The 
attempt  to  substitute  other  theories,  to  assign  other  laws  of 
force,  may  be  deemed  the  wandering  of  an  erratic  mind, 
or  the  presumption  of  an  ignorant  man.  But  this  research 
was  commenced  without  reference  to  the  public,  and  the 
results  are  presented,  not  presumptuously,  but  firmly, — not 
with  the  belief  that  we  have  fully  developed  the  truth, 
that  all  our  views  are  sound,  that  no  mistakes  are  made, 
but  with  the  conviction  that  our  speculations  are  founded 


MECHANICAL  PHILOSOPHY.  81 

upon  principles  that  fully  deserve  attention  and  examination. 
We  appeal  to  those  who  believe  that  there  is  yet  hope  of 
progress  in  philosophy. 

Attraction,  as  coming  under  human  observation,  is  mainly 
believed  on  considerations  derived  from  the  fall  of  bodies  to 
the  earth,  and  from  their  supposed  weight  or  pressure  when 
at  rest.  This  is  the  foundation  of  the  theory.  All  else 
is  assumption  or  deduction.  The  mutual  attraction  of 
different  masses  at  the  surface  of  the  earth  is  supposed  to 
corroborate  the  theory  ;  but  from  the  utter  impossibility  of 
measuring  this  slight  action,  or  even  of  ascertaining  if  there 
be  any,  the  mutual  attraction  of  the  minor  masses  being 
overwhelmed  by  the  immense  comparative  mass  of  the 
earth,  it  is  a  proof  about  as  conclusive  as  that  the  sun 
shines  because  a  fixed  star  twinkles.  The  doctrine  of  at- 
traction, therefore,  rests  on  the  observed  fact  that  bodies 
unsupported  fall  to  the  earth. 

If,  therefore,  the  descent  of  a  body  can  be  fully  accounted 
for  by  the  spare  force  of  rotation  at  a  lower  level,  and  its 
weight  or  pressure  by  the  fact  that  it  requires  force  to  lift 
it  up  to  a  higher  level,  the  reason  on  which  the  theory  of 
gravitation  stands  is  taken  away. 

The  law  of  gravitation  is  not  needed  for  the  motion  of  the 
heavenly  bodies.  There  is  more  truth  to  nature,  there  is 
more  simplicity  and  beauty  in  the  idea  that  the  force  of  the 
revolving  body  is  within  itself ;  that  its  curvilinear  motion  is 
its  natural  motion  ;  that  it  goes  round  in  its  orbit  without 
needing  the  guidance  and  direction  of  central  and  tangential 
forces ;  that  it  can  be  trusted  to  the  unerring  energy 
imparted  to  it  from  the  beginning.  It  needs  no  great  pre- 
sumption thus  to  affirm ;  for  by  ancient  philosophers,  and 
in  more  recent  times  by  Copernicus,  Galileo,  Kepler,  Des 


82  OUTLINES  "OF   A   SYSTEM   OF 

Cartes,  it  was  believed  that  circular  motion  was  the  natural 
motion. 

Nor  is  the  general  acceptation  of  a  theory  any  proof  that 
it  is  the  most  true  and  most  perfect  theory  that  will  ever  be 
presented.  How  long  endured  the  Ptolemaic  system  of 
astronomy,  how  firm  was  the  belief  of  men  in  its  truth ! 
Those  who  first  questioned  it,  those  who  first  doubted  that 
the  sun  revolved  around  the  earth,  were  not  only  deemed 
unsound  in  reason,  but  "  diabolical  and  wicked,"  and  were 
visited  by  the  vengeance  of  the  offended  good  sense  of 
man.  Extensive,  too,  was  the  sway  of  the  theory  of  Des 
Cartes,  which  preceded  the  theory  of  gravitation.  The 
Cartesian  hypothesis,  representing  the  worlds  as  moved  by 
vortices  of  revolving  matter,  and  the  fall  of  bodies  as 
motion  downward  by  the  decrease  of  the  range  of  the  vor- 
tex, they  sinking  to  the  lowest  part  of  the  whirlpool,  held 
for  a  while  an  even  contest  with  the  hypothesis  of  gravita- 
tion, the  battle  hanging  long  with  doubtful  issue.  Because 
it  was  decided  at  last  in  favor  of  the  Newtonian  school,  is  it 
to  be  supposed  that  the  speculations  of  that  truly  great  man, 
Des  Cartes,  were  all  absurd,  that  he  affirmed  no  truth, 
that  Newton  was  right  in  all  his  affirmations,  and  that 
the  power  of  progress  expired  with  his  life  ?  How  great 
were  Galileo,  Copernicus,  Leibnitz,  Kepler !  Yet  who  takes 
for  granted  all  that  they  asserted  ?  To  see  truth  fitfully, 
through  the  obscurity  of  error,  is  the  most  that  can  be  hoped 
for  by  any  man.  or  can  be  claimed  as  the  result  of  the  labors 
of  any  philosopher. 

Among  the  minds  distinguished  as  far  surpassing  in 
power  the  range  of  ordinary  intellects,  was  that  of  Kepler. 
He  seemed,  on  some  points  at  least,  to  have  an  intuitive  per- 
ception of  truth,  and  his  discoveries  have  led  to  extended 


MECHANICAL   PHILOSOPHY.  83 

practical  results.  His  determinations  of  the  laws  of  plan- 
etary motion  are,  and  must  ever  continue  to  be,  the  basis  of 
knowledge  in  astronomy.  Yet  even  he  believed  that  the 
earth  was  an  animal,  and  many  of  his  other  ideas  create  a 
smile,  they  appear  so  fanciful  and  absurd  ;  but  fanciful 
and  absurd  because  time  and  further  observation  have 
refuted  them. 

It  is  no  evidence  of  a  want  of  reverence  for  the 
great,  that  we  believe  and  assert  that  no  individual  is 
without  error  or  has  attained  the  whole  truth  ;  that  no 
authority,  however  great,  should  determine  and  settle  every 
principle  in  philosophy.  "  There  were  giants  in  those 
days  ;"  but  so  long  as  the  race  of  man  exists  there  will  be 
strength. 

"  Why,"  said  a  very  great  man,  far  back  in  the  ages  of 
time,  u  why  is  it  that  neither  very  small  nor  very  large 
bodies  go  far  when  we  throw  them,  but  in  order  that  this 
may  happen  the  thing  thrown  must  have  a  certain  propor- 
tion to  the  agent  which  throws  it  ?  Is  it  that  the  thing 
which  is  thrown  must  react  against  the  thing  which  pushes 
it ;  and  that  a  body  so  large  as  not  to  yield  at  all,  or  so 
small  as  to  yield  entirely  and  not  to  react,  produces  no 
throw  or  push?"  Should  the  human  mind  have  rested 
upon  philosophy  like  this  ?  By  no  means.  The  theories  of 
philosophy  are  not  truth,  but  monuments  set  up  to  mark  the 
progress  of  man  in  his  search  for  truth,  —  guides  in  the 
path  which  leads  to  the  truth.  We  should  read  with  rever- 
ence for  the  great  minds  of  olden  times,  while  rejoicing  in 
the  advance  which  present  opinions  indicate  ;  we  should 
read  present  opinions  in  the  belief  that  they  also  will  serve 
future  generations  to  mark  a  continued  and  accelerated 
progress  ;  we  should  read  with  respect  for  those  who  have 


84  OUTLINES    OP   A    SYSTEM   OF 

faithfully  discharged  their  trusts,  and  with  confidence  that 
those  who  are  yet  to  do  work  upon  the  earth,  will  do  it  even 
more  successfully,  for  having  the  vantage  ground  of  former 
attainments,  —  the  highest  reach  of  the  minds  of  the  greatest 
men  of  one  century  furnishing  the  elements  of  thought  to 
the  succeeding  age. 

Those  who  reverence  Newton  should  show  their  reverence 
by  imitating  him  in  his  unwearied  and  eager  search  for  new 
truth.  He  was  not  satisfied  with  philosophy  as  he  found  it ; 
but,  taking  the  floating  theories  of  his  time,  he  employed  his 
immense  intellect  in  giving  them  system,  character,  definite- 
ness,  so  that  his  philosophy,  partaking  of  the  vigor  of  his 
mind,  has  so  long  held  dominion  over  the  world.  Though 
his  name  is  most  intimately  associated  in  the  general  mind 
with  the  theory  of  gravitation,  his  labors  in  this  depart- 
ment used  but  a  small  portion  of  his  energy.  Every  sub- 
ject in  the  vast  range  of  subjects  to  which  he  directed 
his  attention  retains  the  marks  of  his  strength.  He  is 
often  thought  of  as  a  mere  mathematician,  verifying  the 
ideas  of  others.  Far  from  it.  His  originality  of  mind 
equalled  his  mathematical  exactness  of  conception.  How 
eagerly  did  he  seize  upon  every  new  truth,  how  ready  was 
his  mind  for  progress  !  The  contemplation  of  such  a  char- 
acter should  prevent  us  from  ever  remaining  satisfied  with 
ideas  to  which  the  least  doubt  can  be  attached. 


CHAPTER  V. 


"  IN  THE  CONSTANT  OSCILLATION  OP  THE  HUMAN  MIND  BETWEEN 
IDEAS  AND  FACTS,  AFTER  HAVING  FOR  A  MOMENT  TOUCHED  THE 
LATTER,  IT  SEEMS  TO  SWING  BACK  MORE  IMPETUOUSLY  TO  THE 

FORMER." —  Whewell 

WE  pass  from  the  examination  of  the  very  minute  and  of 
the  far-extended,  to  the  common  facts  of  our  daily  observa- 
tion ;  gladly  throwing  down  the  telescope  and  microscope, 
we  will  look  with  the  naked  eye  at  nature  in  the  ordinary 
range  of  vision. 

Were  we  to  select  one  class  of  facts  to  illustrate  the  ideas 
we  present,  and  to  disprove  the  attraction  of  matter,  it 
would  be  that  which  relates  to  oscillatory  motion,  —  the 
action  of  the  pendulum  and  kindred  movements. 

The  swing  of  a  pendulum,  increasing  in  velocity  in  pro- 
portion to  the  decrease  of  distance  from  the  centre  of  oscil- 
lation, the  force  of  its  motion  being  measurable  by  the  area 
of  the  circle  of  which  it  describes  a  segment,  shows  that  the 
nature  of  force  is  the  same,  however  its  energies  may 
operate.  It  brings  to  the  mind  the  relative  speed  of  the 
planets,  increasing  as  the  diameter  of  their  orbits  diminishes. 
Its  regular  beats  mark  time  with  the  same  precision  as 
does  the  harmonic  motion  of  the  heavenly  bodies.  It  is, 
therefore,  a  free,  unrestrained  movement,  showing  the  laws 
of  force,  and  had  it  been  rightly  understood,  the  laws  which 
8 


86  OULTINES   OF  A   SYSTEM   OF 

regulate  the  planetary  movements  might  have  been  distinctly 
inferred  from  it.  "  We  feel,"  says  Bailly,  in  his  History  of 
Astronomy,  "  that  nature  is  very  simple  in  her  operations  ; 
the  positions  and  motions  of  the  planets  offer  at  first  sight 
the  appearance  of  intricacy,  but  the  principle  which  impels 
them  has  a  naturalness  and  simplicity  like  the  character  of 
truth ; "  and  this  principle  has  application  not  only  to  them, 
but  to  all  natural  and  unrestrained  motion.  Thus  in  the 
pendulum,  its  orbit  prescribed  and  a  uniform  force  of  impulse 
given,  motion  ensues,  invariable,  equal,  measured  by  the 
area  described. 

A  pendulum  beating  seconds  does  not  change  as  to  time 
of  vibration  with  the  addition  or  subtraction  of  weight,  nor 
with  a  stronger  or  weaker  impulse  given  to  it ;  the  weight  of 
the  mass  moved  and  the  length  of  the  sweep  do  not  change 
the  time,  if  the  same  length  of  rod  is  retained.  The  force 
of  motion  is  ever  in  proportion  to  the  mass,  and  the  stronger 
impulse  only  increases  the  range  of  motion  with  an  increase 
of  velocity  that  gives  the  equal  time.  The  impulse  lifts  it 
higher  and  it  falls  with  greater  rapidity,  and  the  fall  both 
in  distance  and  velocity  determines  the  succeeding  rise.  It 
is  evident,  therefore,  that  this  result  is  produced  by  the 
same  principle  which  occasions  the  fall  of  bodies  to  the 
earth  ;  for  the  downward  force  is  just  the  force  of  a  body 
falling  vertically  the  same  distance,  and  the  rise  is  also  the 
same  both  in  relation  to  distance  and  velocity.  It  is  the 
same  principle  which  causes  the  rise  and  fall  of  a  stone 
thrown  into  the  air,  to  be  in  equal  times.  How  can  this 
equal  rise  and  fall  of  the  pendulum  be  explained  on  the 
theory  of  gravitation  ?  Where  is  the  reference  to  the  centre 
of  attraction,  —  where  the  gravitating  power  ?  How  is  it 
that  the  power  drawing  to  the  earth  draws  and  repels 


MECHANICAL  PHILOSOPHY. 

equally  ?  The  rise  is  unquestionably  a  continuation  of  the 
same  motion  as  the  fall,  proving  that  the  force  has  no  more 
reference  to  a  downward  than  to  an  upward  attraction. 

Galileo  first  called  attention  to  the  fact  that  in  the  case 
of  a  stone  swung  by  a  string,  the  time  of  its  rise  was  equal 
to  the  time  of  its  fall  without  reference  to  the  path  or  orbit 
of  its  rise  ;  thus  pointing  to  the  truth  that  oscillation  is  but 
the  transfer  and  retransfer  of  the  force  of  rotation,  and  that, 
consequently,  the  force  disengaged  by  the  fall  is  the  force 
which  occasions  the  rise.  The  force  is  produced  by  the 
descent,  and  is  absorbed  by  the  ascent ;  it  is  in  proportion 
to  the  degree  of  descent,  and  is  necessary  for  the  same  de- 
gree of  ascent ;  the  degree  of  force  is  proportional  to  the 
change  of  level,  one  mean  level  being  ever  preserved  in  all 
oscillation.  Therefore,  the  cause  of  oscillation  is  to  be 
referred  to  the  moving  body  and  not  to  the  earth. 

We  repeat  the  idea ;  the  force  by  which  the  oscillating 
body  moves  is  the  force  disengaged  from  rotation  by  the 
decrease  of  the  level  of  rotation.  It  is  the  unseen  force  by 
which  all  things  move  in  their  diurnal  round,  for  a  moment 
becoming  visible  in  the  curve  of  the  pendulum,  as  the  un- 
seen motes  floating  in  the  air  show  themselves  for  an  instant 
in  passing  through  the  beams  of  the  sun. 

From  the  view  we  have  taken  it  will  be  perceived,  that  as 
the  pendulum  preserves  one  mean  level,  and  as  its  force  of 
descent  is,  as  it  were,  annihilated  by  its  ascent,  it  can  neither 
communicate  force,  nor  be  the  source  of  any  motive  power. 
We  can  also  understand  the  manner  in  which  the  force  of 
impulse  acts  ;  it  gives  the  elevation  by  the  descent  from 
which  force  is  produced.  Practically,  to  continue  the  oscil- 
lation of  the  pendulum,  force  of  impulse,  as  by  the  weight  of 
the  clock,  must  be  added  continually  ;  for  a  single  impulse  of 


88  OUTLINES   OF  A   SYSTEM   OP 

elevation  is  soon  lost  by  friction,  and  by  the  force  taken  to 
move  away  the  air  from  the  path  of  the  vibrating  mass.  In  a 
vacuum  and  without  friction,  the  pendulum  would  continue 
to  act  without  a  renewal  of  the  impulse.  To  understand 
oscillation,  we  should  separate  in  our  minds  the  cause  of 
oscillation,  —  the  transfer  of  rotative  force  to  other  motion 
and  its  reapplication  to  rotation,  —  from  the  impulse  which 
first  elevates  the  mass  to  the  position  from  which  it  falls, 
and  which  is  only  the  condition  of  oscillation. 

This  view  of  the  subject  takes  away  many  of  the  abstrac- 
tions which  have  been  connected  with  the  action  of  the  lever, 
and  with  the  motions  of  bodies  in  equilibrio.  It  throws  over 
all  connected  subjects  a  plain  and  intelligible  law.  The 
mind  escapes  from  embarrassment.  What  more  simple  idea 
can  we  have  in  relation  to  the  action  of  a  lever  of  unequal 
arms,  where  a  smaller  weight  balances  a  larger  weight  and 
oscillates  with  it,  than  to  know  that  one  in  proportion  to  the 
mass  ascends  in  the  degree  in  which  the  other  descends, 
the  greater  descent  of  the  smaller  weight  affording  sufficient 
force  for  the  less  ascent  of  the  larger  weight,  and  the  con- 
verse ?  How  difficult  to  conceive  that  the  earth,  with  an 
attractive  force  in  propotion  to  its  mass,  could  draw  down  five 
pounds  so  as  to  elevate  ten  pounds,  merely  because  the  two 
unequal  weights  are  at  different  distances  from  a  certain 
fixed  point,  though  at  the  same  distance  from  her  centre ! 

In  a  scale-beam  balanced  by  two  equal  weights,  how  could 
oscillation  take  place  under  the  law  of  gravitation  ?  Yet 
if  you  give  one  of  these  weights  an  impulse,  they  will  oscil- 
late, —  oscillate  forever  in  a  vacuum  without  friction. 
Gravitation  has  no  power  to  give  alternate  motion,  —  at- 
tracting both  weights  with  equal  force,  it  cannot  first  make 
one  heavier  and  then  the  other.  If  both  were  held  with 


MECHANICAL   PHILOSOPHY.  89 

equal  strength,  it  would  be  absolutely  impossible  for  this 
vibration  to  take  place  ;  there  is  an  absence  of  all  cause,  or 
tendency,  or  capacity  for  oscillation.  "  Vis  inertias  of  mo- 
tion" gives  no  aid  ;  for  the  motion  is  suspended  and  renewed 
at  every  vibration.  Nor  does  "  action  and  reaction;"  for 
the  difficulty  is  to  account  for  the  action.  The  earth  might 
as  reasonably  be  supposed  to  attract  only  one  side  of  an 
evenly  balanced  wheel,  and  thus  give  it  continuous  rotation, 
as  first  to  attract  one  weight  and  then  another,  when  both 
weights  are  equally  heavy.  The  motion  is  unquestionably 
from  the  transfer  and  retransfer  of  rotative  force.  The 
balance  rotates  as  one  mass  with  one  degree  of  force,  but 
this  force  flows  from  one  part  to  the  other  of  the  mass. 

So  far  from  being  able  to  induce  oscillation,  the  law  of 
gravitation  would  immediately  overcome  the  motion.  The 
power  of  attraction,  it  is  said,  mcreases  with  the  decrease, 
and  decreases  with  the  increase  of  the  distance  from  the 
centre  of  attraction.  The  weight  going  down  is  therefore 
more  forcibly  attracted,  the  weight  going  up  is  more  feebly 
attracted,  and  this  in  an  increasing  ratio,  both  for  the  de- 
pression and  for  the  elevation.  The  difference,  it  may  be 
said,  is  so  slight,  that  its  results  can  never  be  detected  by 
observation.  But  slight  as  may  be  this  want  of  equilibrium, 
it  actually  exists.  Balances  have  been  made  so  perfect  and 
so  nicely  adjusted,  as  to  turn  by  the  impulse  of  the  thou- 
sandth part  of  a  grain.  Suppose  a  perfect  balance  without 
friction  at  the  fulcrum,  and  acting  in  a  vacuum.  Here 
this  want  of  equilibrium  would  be  felt;  the  descending 
weight,  being  more  attracted,  could  not  rise  ;  the  ascending 
weight,  less  attracted,  could  not  fall.  There  could  be  no 
oscillation  under  the  law  of  gravitation. 

Thus  nature  in  the  vast  range  of  her  adjustments  would  feel 

8* 


90  OUTLINES   OF   A    SYSTEM   OP 

and  respond  to  this  difference  of  attractive  power  at  the 
differing  distances  from  the  centre  of  attraction.  Through- 
out extended  space  there  could  be  no  oscillatory  movement. 
The  spheres,  according  to  theory,  evenly  balanced  in  their 
orbits  by  the  central  and  tangential  forces,  would,  by  mu- 
tual attraction,  have  erratic  movements.  There  would  be 
perturbations,  actual  perturbations,  —  wanderings,  actual 
wanderings,  from  their  path  under  the  increasing  power  of 
the  lessening  distance.  Their  changes  could  not  be  com- 
pensatory and  periodic  ;  the  mean  time  of  revolution  and 
mean  extent  of  axis  of  orbit  could  not  be  preserved  ;  they 
would  aberrate,  but  never  oscillate,  for  the  force  causing 
aberration  would  be  increased  by  the  act  of  aberration. 

On  this  earth  too,  under  the  law  of  gravitation,  the  order 
of  nature  would  be  broken  up.  Off  the  Cape  of  Good 
Hope,  there  are  at  times  waves  more  than  a  half  mile  in 
breadth,  and  very  many  miles  in  length.  Millions  and 
millions  of  tons  of  water  are  thus  heaped  up  in  one  volume  ; 
the  increase  and  diminution  of  attraction  in  this  case  would 
be  felt  and  responded  to,  for  there  are  out  of  balance  thou- 
sands of  tons.  It  must  be  that  the  ascending  water  would 
continue  to  rise,  and  the  valley  of  depression  to  sink  lower. 
What  too  would  be  the  result  of  the  great  tidal  wave  raising 
and  depressing  the  waters  of  an  ocean  ?  Quietly  to  sink 
the  less  attracted  elevation,  and  abruptly  to  lift  the  more 
strongly  attracted  depression  ?  Impossible  ;  under  the  law 
of  gravitation  there  can  be  no  bound  or  limit,  no  oscillation 
whatever.  Perturbation,  swerving  motion,  is  without  check. 
There  is  no  voice  of  command,  Thus  far  and  no  farther 
shalt  thou  rise,  and  here  shall  thy  proud  waves  be  stayed. 

But  on  the  other  hand,  in  the  hypothesis  we  offer,  oscilla- 
tion is  measured  in  its  extent  by  the  impulse.  The  force  of 


MECHANICAL   PHILOSOPHY. 

the  undulation  is  neither  an  increasing  nor  a  diminishing 
force.  It  is  not  acquired  from  other  bodies,  nor  imparted. 
It  exists  in  the  mass  moved,  and  is  transferred  from  part  to 
part.  It  is  a  current  of  force  flowing  by  an  impulse.  This 
idea  will  be  further  elucidated  as  we  proceed,  and  a  prin- 
ciple will  be  unfolded  by  which  the  oscillation  of  all  fluids 
is  limited  within  a  definite  range,  so  that  the  equipoised  and 
freely  moving  element,  water,  has  a  fixed  bound  to  its 
oscillations. 

We  would  rest  the  truth  of  the  hypothesis  on  this  nice 
adjustment,  this  beautiful  equipoise  of  motion  by  which  is 
secured  the  permanence  and  harmony  of  creation ;  and 
with  these  ideas,  the  rise  of  the  wave  reflects  from  its  spray 
not  only  the  light  of  the  sun,  but  its  motion  reflects  to  the 
mind  a  more  beautiful  light,  —  light  revealing  the  law  of 
nature,  by  which  movements  as  free  as  the  breath  of  the 
breeze  are  held  in  subjection  with  a  chain  so  strong,  that 
He  only  who  forged  it  can  rend  it  asunder. 

We  will  now  recur  more  particularly  to  the  phenomena 
of  the  waves.  To  show  that  they  are  not  distinctly  under- 
stood, we  will  cite  the  following  description  from  a  standard 
work  on  Natural  Philosophy: — "  Certain  particles  of  water 
are  first  forced  down,  and  the  surrounding  particles  are 
forced  up  above  their  level ;  their  circular  ridge  subsides, 
and  not  only  fills  up  the  original  depression,  but  from  its 
momentum  forces  up  another  ridge  exterior  to  it ;  this  sub- 
siding forces  up  another  ridge,  and  so  on."  This  descrip- 
tion calls  to  mind  the  following  passage  from  an  ancient 
philosopher :  —  "  His  whole  performance  seemed  to  reach  no 
further  than  if  a  man  should  say,  '  Socrates  does  all  by 
intellect,'  and  after  proposing  to  give  a  reason  for  my  action 


92  OUTLINES    OF   A   SYSTEM    OF 

should  say,  *  I  am  sitting  on  my  bed,  because  my  body  is 
composed  of  bones  and  nerves ;  the  bones  are  hard,  solid, 
and  separated  by  joints,  and  the  nerves  being  able  to  bend 
and  unbend  themselves  tie  the  bones  to  the  flesh,  &c.,  and 
that  is  the  reason  forsooth  that  I  sit  in  this  position.' ' 

But  we  need  an  explanation  of  the  phenomena  of  the 
waves  more  distinct  than  comes  from  the  mere  recital  of  the 
phases  of  their  rise  and  fall.  It  is  expressly  mentioned  by 
Plutarch,  and  by  Pliny,  that  the  seamen  of  their  day  used 
to  still  the  waves  by  pouring  oil  into  the  sea.  A  letter  writ- 
ten in  1707,  speaks  of  a  storm  at  sea  "  which  had  nothing 
particular  about  it,  except  that  the  captain  found  himself 
obliged  to  pour  oil  in  the  sea,  which  had  an  excellent  effect, 
and  succeeded  in  preserving  us."  Franklin,  in  his  paper 
on  this  subject,  says :  —  "A  small  quantity  of  oil,  for  in- 
stance, a  quarter  of  an  ounce,  will  spread  itself  quickly  on 
the  water  in  a  pond  to  the  extent  of  an  acre,  and  if  poured 
on  the  windward  side,  the  water  will  thereby  be  rendered 
quite  smooth  as  far  as  the  film  of  oil  extends Its  prin- 
cipal operation  is  to  prevent  the  rising  of  new  waves,  and  to 
prevent  the  wind  from  driving  those  already  raised  with  as 
much  force  as  it  would  if  their  surface  was  not  oiled." 

This  idea  of  stilling  the  waves  by  means  of  oil  is  omitted 
in  recent  works  on  the  subject,  and  is  considered  by  many 
as  a  popular  superstition ;  but  when  was  Franklin  mistaken 
in  facts  which  he  investigated  ?  and  what  popular  belief  is 
there  thus  extensive  which  has  no  foundation  in  truth  ? 
Why  is  it,  as  before  stated,  that  a  thin  stratum  of  oil  spread 
over  the  surface  of  water,  will  prevent  its  freezing  when 
exposed  to  a  degree  of  cold  much  below  the  point  of  conge- 
lation ?  Why  does  oil  prevent  the  adhesion  of  substances 
pressed  together  ?  All  these  results  are  from  the  non-con- 


MECHANICAL  PHILOSOPHY.  93 

ducting  properties  of  oil.  Force  as  heat  does  not  escape 
through  it ;  force  of  cohesion  does  not  pass  this  barrier ; 
force  to  give  the  impulse  which  occasions  the  undulation  of 
the  waves,  is  repelled  from  the  water.  The  theory  of  the 
identity  of  force  a  priori,  without  experiment,  would  have 
indicated  these  results. 

A  fact  analogous  to  the  rise  of  the  wave,  is  the  rise  of  the 
air  in  a  ventilating  tube  ;  over  the  upper  orifice  passes 
the  horizontal  wind,  particles  of  which,  by  their  friction 
or  attrition  on  the  air  in  the  tube,  are  arrested  in  their 
course  ;  the  force  by  which  they  were  impelled  is  imparted 
to  the  air  in  the  ventilating  tube,  and  consequently  the  air 
is  raised  to  a  higher  level  of  rotation.  Wherever  there  is  a 
passage  of  a  current  of  matter,  any  part  of  which  is  arrested 
in  its  course,  that  which  arrests  it  is  moved.  With  this 
idea  fixed  in  the  mind  we  are  able,  not  only  to  give  a  satis- 
factory explanation  of  the  rise  of  the  wave,  but  also  of 
many  common  facts  coming  under  our  daily  observation. 

When  the  wind  passes  over  the  surface  of  the  sea,  parti- 
cles of  this  aerial  current  are  arrested  in  their  course  by 
any  projecting  inequality,  or  in  the  absence  of  already 
formed  waves,  by  friction  or  attrition,  as  already  explained. 
The  water  has  additional  force  transferred  to  it  by  the 
passing  wind.  It  acquires  force  for  rotation  at  a  higher 
level.  It  therefore  rises.  The  elevation  of  the  first  wave, 
however  slight,  offers  a  greater  impinging  surface  ;  it  there- 
fore continues  to  rise,  and  its  rise  is  proportional  to  the 
strength  of  the  wind  which  causes  it.  This  undulation  of 
the  water  arises  from  the  same  principle  as  the  oscillation 
of  the  pendulum,  the  motion  of  which  is  the  reception  and 
transfer  of  the  force  of  rotation  at  its  different  levels  ;  the 
descent  liberates  force  for  the  ascent,  and  one  mean  level 


94  OUTLINES   OF  A   SYSTEM   OF 

of  rotation  is  ever  preserved.  Thus  rises  the  wave,  its 
motion  the  reception  and  transfer  of  force,  its  impulse  of 
oscillation  the  force  robbed  from  the  passing  wind.  Thus, 
and  thus  only,  can  we  explain  a  fact  which  is  rather 
indefinitely  expressed  in  the  following  language  from  high 
authority :  "  Momentum  may  be  accumulated  to  an  enor- 
mous degree  in  very  large  suspended  masses,  by  forces, 
which,  at  their  first  application,  appear  to  be  totally  inade- 
quate to  move  them."  The  impulse  ^s  "  totally  inade- 
quate "  to  cause  the  motion ;  a  child's  hand  cannot  move 
a  thousand  pounds,  but  the  child's  hand  can  destroy  a 
balance,  and  the  force  of  nature  transferred  according  to 
the  level  of  rotation  is  the  cause  of  motion.  In  the  case  of 
the  wave,  the  wind  destroys  the  equilibrium ;  but  the  action 
of  a  more  intense  force  moves  the  mountain  of  waters. 

The  motion  of  the  wave  is  deeply  interesting  in  all  its 
aspects.  The  crests  of  the  surge  rise  vertically,  though 
they  are  apparently  progressive.  It  is  not  until  the  water 
shoals  toward  the  beach  that  they  acquire  a  progressive 
motion,  —  progressive  because  near  the  shore  there  is  not 
depth  for  the  vertical  movement.  It  requires  double  the 
generally  supposed  depth  to  form  the  vertical  wave ;  for 
the  uplifted  water  falls  as  much  below  the  valley  of  depres- 
sion as  it  rises  above  it.  There  is  a  descending  wave,  a 
current  under  water,  which  as  a  wedge  forces  up  the  suc- 
ceeding wave,  an  opposite  wave  under  the  water.  Hence 
on  the  shoaling  water  is  the  undertow,  a  retreat  of  the 
water  at  a  certain  depth  with  advancing  water  at  the  sur- 
face. The  extent  of  this  reciprocal  wave  is  in  exact  pro- 
portion to  the  extent  of  the  visible  wave. 

Besides,  the  surface  of  the  atmosphere  is  also  to  a  degree 
in  oscillation  with  the  water  over  which  it  is  spread.  The 


MECHANICAL    PHILOSOPHY.  95 

•wind  conforms  to  the  surface,  it  oscillates  with  the  water  ; 
the  sails  of  a  boat,  or  the  lower  sails  of  a  ship,  are  not 
becalmed  with  a  steady  wind,  though  surrounded  by  a  wall 
of  water.  Says  an  experienced  navigator,  "  the  lower  sails 
in  scudding  are  at  times  becalmed,  from  the  rise  of  the  stern 
of  the  ship,  but  never  becalmed  on  the  wind,  though  the 
waves  rise  higher  than  the  sails,  a  fact  which  I  have  often 
tried  to  account  for."  For  this  reason,  —  the  undulating 
motion  of  the  wind  over  the  undulating  surface  of  the  sea,  — 
is  it  that  the  wind  off  shore,  not  having  acquired  the  cor- 
responding undulation,  however  strong  it  may  blow,  smooths 
the  sea. 

A  most  interesting  scene  was  described  by  a  friend,  who 
stood  on  a  small  rocky  island  in  the  midst  of  the  ocean, 
looking  with  intense  delight  on  the  forces  of  nature  as 
displayed  in  a  storm.  The  mountain  waves  were  dark, 
almost  black,  the  intensity  of  their  gloom  being  heightened 
by  the  circle  of  white  foam  which  surged  upon  the  rocks. 
A  sudden  veering  of  the  wind,  this  wind  being  without 
the  conforming  undulation,  prostrated  the  billows  as  it  were 
at  once  ;  the  ocean  became  as  smooth  as  in  a  summer's 
breeze.  There  was  no  surge  on  the  rock ;  but  the  surface 
of  the  sea  was  white  with  foam  and  curling  in  wreaths  of 
vapor  as  far  as  the  eye  could  reach.  Gradually,  however, 
the  new  wind  acquired  the  sympathetic  undulating  move- 
ment, the  waves  again  began  to  rise,  and  soon  the  surf 
dashed  with  its  former  fury  against  the  island. 

Only  because  the  rise  and  fall  of  the  wave  are  from  the 
reception  and  transfer  of  force,  the  mean  level  of  the 
ocean  ever  remaining  the  same,  could  this  result  have 
been  produced.  If  there  had  been  "  accumulation  of  mo- 
mentum to  an  enormous  degree,"  —>•  if  the  attracting  earth 


96  OUTLINES    OF   A   SYSTEM   OF 

had  drawn  down  the  depressed  waters  with  more  strength 
than  the  elevated  waters,  —  the  ocean  could  never  have 
been  thus  smoothed  into  the  quiet  of  one  level ;  the  new 
wind  would  have  increased  the  surging  waves,  so  that  they 
would  have  lifted  their  crests  still  higher  in  confused  and 
broken  masses,  resulting  in  a  conflict  of  motion  which  the 
strength  of  no  vessel  that  ever  floated  could  withstand. 
There  is  something  fascinating  in  the  contemplation  of  the 
intensity  of  the  force  of  the  elements  so  perfectly  under  the 
control  of  law,  as  is  witnessed  on  the  barren  rocks  in  the 
midst  of  the  ocean's  storm. 

Before  passing  to  other  instances  of  oscillatory  move- 
ment, we  will  notice  some  analogous  phenomena.  The  whirl- 
pool and  the  whirlwind  are  illustrative  of  the  action  of  force. 
We  will  copy  first  a  description  of  these  phenomena  which 
contains  their  usual  explanation.  "  When  gusts  of  wind 
come  from  different  quarters,  and  meet  in  a  certain  place, 
there  the  air  acquires  a  circular,  or  rotatory,  or  screw-like 
motion,  either  ascending  or  descending,  as  it  were,  around 
an  axis  ;  and  this  axis  is  sometimes  stationary,  and  at  other 
times  moves  in  a  particular  direction.  This  phenomenon, 
which  is  called  a  whirlwind,  gives  a  whirling  motion  to  dust, 
sand,  water,  a  part  of  a  cloud,  and  sometimes  to  bodies  of 
great  weight  and  bulk,  carrying  them  upwards  and  down- 
wards, and  at  last  scattering  them  in  every  direction.  The 
water-spout  is  formed  by  the  centrifugal  force  of  the  wind, 
creating  a  vacuum  in  the  centre  through  which  the  water 
ascends."  These  are  the  common  ideas  ;  for  circular  motion 
is  usually  considered  as  the  result  of  conflicting  forces. 

The  action  of  two  currents  of  water,  in  the  formation  of 
the  whirlpool,  and  of  two  winds  in  the  formation  of  the 
whirlwind,  is  precisely  the  same.  The  onward  motion  of  the 


MECHANICAL  PHILOSOPHY.  97 

particles  of  water  or  air  is  arrested  by  the  impingement  of 
the  two  currents,  but  the  force  which  impelled  them  is  not 
annihilated  ;  the  onward  motion  only  is  ended,  and  the 
force  from  its  nature  must  produce  motion.  The  circular 
is  the  only  open  range  of  action  ;  for  no  separate  particle  of 
either  stream  can  be  accelerated  in  the  stream  by  a  sudden 
impulse.  Therefore,  the  arrested  water  or  air  moves  in  a 
vortex  until  its  force  is  gradually  imparted  to  the  current  in 
which  it  floats. 

In  the  water-spout  a  part  of  the  force  of  the  revolving 
wind  is  conveyed  to  the  water ;  the  water,  having  force  for 
rotation  at  the  higher  level  thus  communicated  to  it,  rises. 
The  water  on  which  the  whirlwind  rests  becomes  violently 
agitated  with  the  additional  force  received,  and  is  elevated 
as  foam,  vapor,  and  water  and  air  mingled  together.  Of  one 
an  observer  said,  "  the  water  at  the  base  seemed  to  boil 
and  go  up  in  detached  masses  mingled  with  the  air."  The 
raising  of  heavy  bodies  on  the  land  and  of  the  water  of  the 
sea  by  whirlwinds,  in  fact,  the  elevation  of  matter  gen- 
erally, is  ever  on  the  condition  that  the  due  degree  of  rota- 
tive force  is  supplied.  It  may  be  supplied  from  below,  as 
in  the  act  of  pushing  up ;  it  may  be  supplied  from  above  in 
the  act  of  drawing  up.  All  the  phenomena  of  change  of 
level  are  explained  on  this  principle ;  the  falling  body 
imparts  its  no  longer  needed  force,  the  rising  body  demands 
an  increased  supply. 

This  idea  is  finely  illustrated  in  the  fall  of  water  from  a 
great  height  into  a  basin  of  stone,  as  in  the  "Pool"  at  the 
White  Mountains.  The  water  received  in  the  basin  de- 
scends from  a  great  elevation  ;  it  has  great  spare  force  of 
rotation,  which  force,  not  transferred  to  the  rock  on  which 
it  falls,  impels  the  water  in  a  vertical  movement,  and  thus 

9 


98  OUTLINES    OF   A    SYSTEM   OF 

forms  for  itself  a  circular  receptacle.  If  the  water  had 
barely  flowed  into  this  receptacle  without  force,  or  from  a 
moderate  elevation,  the  issuing  water  would  have  used  this 
force,  a  current  between  the  inlet  and  outlet  would  have 
been  established,  and  no  vertical  movement  been  induced. 
Water  arrested  between  two  currents  makes  the  whirl- 
pool. Arrested  water  from  a  great  fall  only,  can  make  a 
permanent  whirlpool,  which  will  scoop  out  for  itself  the 
vortex  mould  from  the  solid  rock. 

A  fact  which  has  strayed  somewhat  from  all  theories, 
and  which  the  books  on  Hydrodynamics  that  we  have 
examined  do  not  even  notice,  —  a  trivial  fact,  coming  under 
our  daily  observation,  —  is  fully  illustrative  of  the  principle  ; 
we  refer  to  the  vortex  in  the  body  of  a  tunnel  full  of  water, 
which  is  formed  on  the  issue  of  the  water  from  the  pipe 
below.  Fill  a  tunnel  with  water ;  when  it  is  stationary 
allow  it  to  flow  out  from  the  pipe  ;  the  water  in  the  tunnel 
immediately  assumes  a  vortical  movement,  and  whirls  faster 
and  faster  as  it  descends. 

We  have  inquired  of  many  who  were  well  read  in  the 
usual  explanations  of  philosophy,  and  their  answer  has  been 
that  the  cause  of  this  vortex  is  the  conflict  of  two  forces. 
How  is  this  ?  By  theory,  there  is  only  one  force  present, 
the  force  of  gravitation,  the  downward  drawing  force  of  the 
attraction  of  the  earth.  One  suggested  that  the  vortex  was 
formed  by  reason  of  the  conical  shape  of  the  tunnel ;  that 
he  was  wrong  is  evident  from  the  fact,  that  a  tunnel  of  any 
form  gives  the  same  result. 

The  explanation  of  the  fact  is  very  simple  on  the  principle 
which  we  present.  The  water  issuing  from  the  tube  uses, 
in  its  downward  motion,  all  the  spare  force  of  its  own 
descent  to  a  lower  level.  But  the  water  remaining  in  the 


MECHANICAL  PHILOSOPHY. 

tunnel  has  also  descended  to  a  lower  level  of  rotation.  It 
has  therefore  spare  force,  and  this  force  has  no  other  range 
than  to  confer  circular  motion  to  the  water.  The  water 
therefore  revolves.  Thus  is  it,  that  facts,  common,  trivial 
facts,  declare  the  general  law. 

We  return  from  this  digression  to  oscillatory  movements, 
and  affirm  that  the  surface  or  crust  of  the  globe,  as  it  has 
been  called,  has  undulatory  motion. 

We  think  that  we  shall  be  able,  as  we  proceed,  to  establish 
the  fact,  that  the  barometer  indicates,  not  the  density  of 
the  atmosphere  and  consequently  the  level  of  rotation,  but 
that  it  indicates  this  level  positively  and  directly.  For  the 
present,  however,  take  the  barometer  as  it  is  commonly 
understood,  as  indicating  by  the  oscillations  of  the  mercury 
the  density  of  the  atmosphere. 

There  are  oscillations  of  the  mercury  entirely  unac- 
counted for  by  this  theory.  At  the  same  apparent  level 
the  barometer  has  a  range  of  about  three  inches.  This 
well  known  fact  cannot  be  explained  by  any  supposed  varia- 
tion in  the  density  of  the  incumbent  atmosphere.  Philosophy 
acknowledges  her  ignorance  of  the  cause  of  these  changes. 
The  dryness  or  the  humidity  of  the  air  will  not  account  for 
them  ;  this  is  admitted.  Winds  cannot  give  the  reason ; 
for  it  would  require  the  passage  of  a  current  of  air  two 
thousand  eight  hundred  and  eighty  miles,  at  the  rate  of 
sixty  miles  an  hour,  to  account  for  a  variation  of  one  half 
inch  of  the  mercury.  Besides,  these  changes  often  precede 
the  change  in  the  atmosphere  ;  they  may  take  place  when 
there  is  a  dead  calm,  or  during  the  blowing  of  a  steady 
gale,  thus  foretelling  atmospheric  changes  rather  than  being 
produced  by  them.  Do  not  these  facts  indicate  that  the 
same  cause  which  changes  the  level  of  the  barometer  pro- 


100  OUTLINES    OF   A    SYSTEM    OF 

duces  the  change  in  the  atmosphere,  not  that  the  atmos- 
pheric change  affects  the  barometer  ? 

These  oscillations  of  the  mercury  are  not  without  cause, 
and  there  is  one  cause  to  which  we  would  assign  them, — 
the  rise  and  depression  of  the  earth's  surface  on  which  the 
barometer  stands.  We  believe  that  the  earth  is  to  a  degree 
elastic,  yielding  ;  that  it  is  susceptible  of  undulatory  move- 
ment, —  periodic,  or  occasional,  —  so  extensive  in  range,  yet 
so  slight  in  amount  as  to  produce  no  convulsion,  no  apparent 
change ;  yet  to  be  traced  by  the  oscillations  of  the  barom- 
eter, and  by  the  winds  and  storms  which  indicate  a  new 
distribution  of  the  force  of  rotation. 

A  scientific  writer  says,  that  the  surface  of  the  globe  is  no 
more  stable  or  firm  comparatively  than  is  a  heap  of  saw- 
dust which  is  floating  on  the  surface  of  the  water.  This  is 
a  strong  metaphor,  but  he  drew  his  inference  from  a  suppo- 
sition which  we  are  far  from  believing,  —  from  hidden  fires 
shut  up  in  the  bosom  of  the  earth.  For,  as  he  says,  if  in 
the  same  proportion  the  heat  continues  into  the  interior  of 
the  earth,  which  is  evidenced  by  the  fact  of  its  increase  so 
far  as  we  have  penetrated,  at  one  hundred  miles  from  the 
surface  it  would  be  greater  than  any  artificial  heat  ever 
produced.  The  most  refractory  substances  would  be  reduced 
to  a  fluid  state ;  therefore,  the  solid  crust  is  of  small  com- 
parative depth,  and  the  internal  fires  by  their  intensity  may 
well  be  supposed  to  give  motion  to  it. 

But  there  are  many  well  known  facts  which  prove  that 
there  are  fluctuations  of  the  surface  of  the  globe.  An  ele- 
vation of  the  coast  of  Chili  of  eighty-five  feet  has  been  proved 
by  geologists,  and  a  recent  elevation  of  four  feet,  extending 
along  a  thousand  miles  of  the  South  American  coast,  was 
produced  in  a  single  night.  Earthquakes  have  been  felt 


MECHANICAL  PHILOSOPHY.  101 

throughout  an  entire  hemisphere.  During  the  great  earth- 
quake near  Lisbon,  the  waters  rose  with  the  upheaving 
earth  one  hundred  feet,  and  the  motion  was  propagated 
across  the  Atlantic  Ocean,  vessels  feeling  the  surge 
according  to  their  distance  from  the  centre  of  motion.  We 
would  also  refer  to  the  "  periodic  although  irregularly  alter- 
nating rise  and  fall  of  the  waters  of  the  Caspian  sea,"  and 
to  the  fact  that  harbors  in  the  Mediterranean  sea  have  been 
suddenly  left  dry  for  many  hours.  It  is  stated  by  an  emi- 
nent geologist,  that  the  strata  of  the  earth,  her  ridges,  her 
mountains  and  valleys  take  the  general  form  that  would  be 
induced  by  continuous  undulations ;  and  geologists  generally 
assert  the  same  fact,  referring  it  to  various  causes.  If  there 
be  changes  which  result  in  convulsion,  and  which  thus  leave 
a  permanent  record,  why  may  there  not  be  gentler  changes, 
fluctuations  unattended  with  severe  catastrophes  or  abiding 
results  ?  We  have  the  authority  of  Humboldt  for  the 
assertion,  that  without  earthquakes  the  surface  of  the  earth 
is  capable- of  gentle  and  progressive  oscillations;  and  he 
also  remarks  that  "  the  opinion  so  implicitly  entertained 
regarding  the  force  of  gravity  at  any  given  point  of  the 
earth's  surface,  has  in  some  degree  been  controverted  by  the 
gradual  rise  of  large  portions  of  the  earth's  surface." 

The  sudden  changes  of  level  in  the  waters  of  our  great 
lakes  have  long  excited  attention,  and  have  never  been  sat- 
isfactorily accounted  for.  We  copy  from  the  Annual  of 
Scientific  Discovery  a  condensed  account  of  the  facts  so 
far  as  they  are  known,  and  the  hypotheses  which  are  offered 
for  their  solution.  "  The  results  of  recent  observations  prove 
that  these  waters  do  not  rise  and  fall  at  stated  periods,  cor- 
responding to  the  ebb  and  flow  of  the  tide,  but  are  subject 
to  extraordinary  risings,  which  are  independent  of  the 
9* 


102  OUTLINES   OF  A   SYSTEM   OF 

influence  of  the  -sun  and  moon.  These  risings  attracted  the 
attention  of  the  earliest  voyageurs  in  these  regions.  Char- 
levoix,  who  traversed  the  lakes  nearly  a  century  ago,  says 
in  reference  to  Lake  Ontario :  — '  I  observed  that  in  this 
lake  there  is  a  sort  of  reflux  and  flux,  almost  instantaneous  ; 
the  rocks  near  the  banks  being  covered  with  water  and  un- 
covered again  several  times  in  the  space  of  a  quarter  of  an 
hour,  even  if  the  surface  of  the  lake  was  very  calm,  with 
scarce  a  breath  of  air.  After  reflecting  for  some  time  on 
this  appearance,  I  imagined  it  was  owing  to  springs  at  the 
bottom  of  the  lake,  and  to  the  shock  of  their  currents  with 
those  of  the  rivers  which  fall  into  them  from  all  sides,  and 
thus  produce  those  intermitting  motions.'  The  same  move- 
ments were  noticed  by  Mackenzie,  in  1787  ;  by  an  expedi- 
tion under  Colonel  Bradstreet,  in  1764  ;  on  Lake  Erie,  in 
1823  ;  and  at  various  later  periods.  In  the  summer  of 
1834,  an  extraordinary  retrocession  of  the  waters  of  Lake 
Superior  took  place  at  the  outlet  of  Sault  Sainte  Marie. 
The  river  at  this  place  is  nearly  a  mile  wide,  and  in  the  dis- 
tance of  a  mile  falls  18.5  feet.  The  phenomena  occurred 
about  noon.  The  day  was  calm,  but  cloudy.  The  water 
retired  suddenly,  leaving  the  bed  of  the  river  bare,  except 
for  a  distance  of  thirty  rods,  and  it  remained  so  nearly  an 
hour.  Persons  went  out  and  caught  fish  in  pools  formed  in 
the  depressions  of  the  rocks.  The  return  of  the  waters  is 
represented  as  having  been  very  grand.  They  came  down 
like  an  immense  surge.  In  the  summer  of  1847,  on  one 
occasion  the  waters  rose  and  fell  at  intervals  of  about  fifteen 
minutes,  during  an  entire  afternoon.  The  variation  was 
from  ten  to  twenty  inches,  the  day  being  calm  and  clear ; 
but  the  barometer  was  falling.  Before  the.  expiration  of 
forty-eight  hours  a  violent  gale  set  in.  At  Copper  Harbor, 


MECHANICAL    PHILOSOPHY.  103 

the  ebb  and  flow  of  the  water  through  narrow  inlets  and 
estuaries  have  been  repeatedly  noticed  when  there  was  not  a 
breath  of  wind  on  the  lake.  Similar  phenomena  occur  on 
several  of  the  Swiss  lakes.  Professor  Mather,  who  observed 
the  barometer  at  Copper  Harbor  during  one  of  these  fluctua- 
tions, remarks  :  — c  As  a  general  thing,  fluctuations  in  the 
barometer  accompanied  fluctuations  in  the  level  of  the 
water  ;  but  sometimes  the  water-level  varied  rapidly  in  the 
harbor,  while  no  such  variations  occurred  in  the  barometer 
at  the  place  of  observation.' 

"  As  a  general  rule,  these  variations  in  the  water-level 
indicate  the  approach  of  a  storm,  or  a  disturbed  state  of  the 
atmosphere.  We  are  therefore  led  to  infer  that  these  phe- 
nomena result,  not  from  the  prevalence  of  the  winds  acting 
on  the  water,  accumulating  it  at  one  point  and  depressing 
it  at  others,  but  from  sudden  and  local  changes  in  the  pres- 
sure of  the  atmosphere  giving  rise  to  a  series  of  barometric 
waves." 

How  could  there  be  these  "  sudden  and  local  changes" 
in  the  pressure  of  the  atmosphere,  with  a  calm  day,  and  of 
course  an  equable  temperature  ?  Or  how  could  they  exist 
at  all  in  a  fluid  so  elastic  as  the  air,  the  very  nature  of 
elasticity  being  such  as  to  correct  at  once  any  difference  of 
density  in  the  same  volume  ?  Our  views  lead  us  to  regard 
these  changes  in  the  level  of  the  water  as  indicative  of 
changes  of  the  level  of  those  portions  of  the  earth  on  which 
the  water  rests.  And  as  a  proof  that  vibration  of  the  earth's 
surface  does  occasion  barometrical  change,  we  need  only 
refer  to  the  well-known  fact  that  at  the  time  of  the  great 
Lisbon  earthquake,  the  mercury  fell  so  far  in  the  barometer 
even  in  Great  Britain,  "  as  to  disappear  from  that  portion 
of  the  top  usually  left  uncovered  for  examination."  Hum- 


104  OUTLINES   OF   A   SYSTEM   OF 

boldt  also  remarks  that  "  the  connection  between  the  erup- 
tion of  a  small  volcano  with  the  state  of  the  barometer  is 
generally  recognized,  although  our  present  knowledge  of 
volcanic  phenomena,  and  the  slight  changes  of  atmospheric 
pressure  accompanying  our  winds,  do  not  enable  us  to  offer 
any  satisfactory  explanation  of  the  fact." 

But  we  need  not  accumulate  facts.  Science  generally 
indicates  a  change  of  level  of  different  portions  of  the  crust 
of  this  globe,  taking  place  either  periodically,  or  as  it  were 
incidentally.  Nor  are  we  limited  to  science  for  our  proofs 
of  mutation.  Science  may  point  to  the  barometer  as  indica- 
tive of  these  changes ;  she  may  show  the  earthquake  and 
the  storm ;  she  may  declare,  from  the  upraised  strata,  from 
the  mountain  ridges,  from  the  depressed  valleys,  from  the 
confused  commingling  of  the  primitive,  the  transition,  and 
the  recent  formation,  that  the  earth  is  not  an  unyielding 
mass,  bound  together  by  a  law  which  gives  increased  density 
according  to  the  approach  to  its  centre. 

The  world,  now  permanent  as  the  home  of  man,  has 
passed  through  at  least  one  great  and  sudden  change.  The 
upturned  strata,  the  drift  from  the  poles  so  enormous  in 
quantity,  that  were  it  again  collected  and  restored  it  would 
change  the  form  of  the  earth,  abundantly  prove  this.  We 
know  that  this  great  change  has  been  accounted  for  by 
natural  causes,  by  the  accumulation  of  the  present  changes 
in  foregone  times,  —  by  the  condensation,  as  it  were,  of 
present  events  in  the  lapse  of  past  ages,  —  by  the  volcano, 
the  earthquake,  the  storm,  the  drift  of  rivers,  the  gradual 
deposit  of  floods  ;  —  glaciers  have  been  launched,  and  ice- 
bergs freighted  with  diluvium  and  boulders.  We  are  not  pre- 
pared to  seek  a  solution  of  the  great  changes  of  the  earth 
from  natural  causes,  from  the  intensification  of  the  present 


MECHANICAL    PHILOSOPHY.  105 

action  of  force,  condensed  to  stronger  action  in  the  youth  of 
the  world.  There  has  been  one  change  at  least,  which  came 
not  from  a  natural  cause,  from  the  e very-day  phenomena  of 
nature.  We  refer  to  the  time  when  the  earth  was  without 
form  and  void,  and  darkness  was  on  the  face  of  the  deep, 
when  the  spirit  of  God  moved  on  the  face  of  the  water, 
and  it  was  said,  Let  there  be  light,  and  the  rays  of  the  sun 
created  "  in  the  beginning"  for  the  first  time  penetrated  the 
mist  that  went  up  from  the  surface  of  the  earth  ;  when  "  the 
firmaments  rose  "  and  "  divided  the  waters  from  the  waters." 

How  great  the  change  which  thus  converted  a  chaotic 
world  into  a  bright  and  beautiful  home  for  man  !  The 
intensity  of  the  force  is  written  down  on  the  broken  strata, 
the  torn  and  ragged  mountain  ridges,  and  in  the  smoothing 
and  furrowing  of  the  stubborn  rocks.  The  form  of  the 
earth  was  changed,  and  with  this  change  came  necessarily 
a  change  of  its  rotation,  and  it  may  be  of  the  form  of  its 
orbit ;  for  a  change  in  one  condition  of  a  sphere,  must 
change  its  every  phase. 

And  that  this  change  did  take  place  proves  that  there 
can  be  no  reference  to  any  supposed  centre  as  the  radiating 
point  of  its  motive  force  ;  for  the  globe  is  self-poised,  asking 
of  no  other  leave  to  be,  borrowing  of  no  other  the  power  to 
move,  —  connected,  as  a  part  of  a  system  of  worlds,  yet 
speeding  on  in  a  path  of  her  own  in  perfect  balance,  in  ac- 
curate equilibrium,  as  if  buoyed  up  by  the  right  arm  of  God. 

As  there  is  a  perfect  equipoise  in  the  earth  as  a  sphere, 
as  a  whole,  so  is  there  the  same  perfect  equipoise  in  her 
parts,  in  her  elements,  in  her  constituting  masses.  From 
this  perfect  equipoise  come  the  slight  aberrations  and  per- 
turbations, the  oscillations  of  the  surface.  As  the  pendulum 
swings  on  the  condition  of  equilibrium  ever  preserving  one 


106  OUTLINES   OF   A   SYSTEM   OF 

mean  level,  so  may  the  surface  vibrate  of  the  even-balanced 
earth.  Therefore  is  there  freedom,  ease,  elasticity  of  mo- 
tion,—  nothing  stationary,  yet  nothing  wandering  to  an 
extent  that  can  mar  the  designs  of  creative  wisdom  ;  all 
things  flowing  gently  as  if  without  rule,  yet  bound  together 
by  laws  as  sure  and  as  unchangeable  as  is  the  power  of  Him 
who  formed  the  earth  in  the  beginning,  as  the  home  of  his 
children,  whose  security  and  happiness  were  the  objects  of 
creative  skill. 

An  idea  given  in  a  sermon  by  the  Rev.  A.  P.  Peabody 
has  fastened  itself  in  our  thoughts  ;  we  quote  from  memory  : 
"  In  the  Ptolemaic  system,  this  earth  was  considered  as  the 
centre  of  the  system  to  which  all  the  wandering  hosts  of 
heaven  were  tributary,  —  aids,  accompanying  circumstances. 
The  better  lights  of  astronomy  dispelled  this  error,  and  the 
earth  is  looked  upon  now  as  a  part,  a  minute  part  of  a  uni- 
verse without  a  conceivable  limit.  But  the  earth  from  this 
is  not  degraded,  but  exalted,  —  not  decreased,  but  increased 
in  interest.  The  part  of  such  a  whole  far  transcends  in 
sublimity  the  centre  of  a  system  so  narrow  that  all  refers  to 
its  own  limited  bounds."  The  idea  extended  to  man  imparts 
to  the  individual  a  dignity  proportional  to  the  extent  of  the 
universe  of  which  he  is  a  participant,  -«-  little  in  himself,  yet 
how  great  considered  as  an  intregral  part  of  the  whole  crea- 
tion !  And  this  intimate  connection,  too,  not  merely  apper* 
tains  to  his  physical  nature,  but  he  has  yet  greater  dignity 
of  position  from  the  view  that,  connected  as  he  is  with  God's 
material  universe,  there  is  also  for  him  a  connection  with  the 
Sustaining  Spirit,  the  Life  of  the  Universe,  •• —  that  indeed 
he  is  the  child  of  God, 

We  return  from  this  "  oscillation "  of  thought,    In  a 


MECHANICAL    PHILOSOPHY.  10T 

still  night,  at  a  hotel  of  great  extent,  built  of  massive 
granite,  a  vibratory  motion  was  distinctly  perceptible. 
This  great  stone  building,  the  adjacent  buildings  of  brick, 
and  the  intervening  ground  to  a  great  extent  were  perceptibly 
moved  by  the  passing  of  a  carriage  over  the  paved  street. 
Did  the  muscular  force  of  the  horse  thus  produce  motion  of 
the  enormous  mass  of  stone,  brick,  earth,  and  the  solid 
ledge  ?  The  impulse  only  was  given,  and  this  impulse, 
slight  as  it  was,  so  nicely  adjusted  is  the  balance  of  force, 
resulted  in  oscillation.  The  vibration  called  forth  by  the 
motion  of  the  carriage,  was  the  bringing  into  action  the 
weight  of  the  mass,  —  the  transfer  and  retransfer  of  the 
force  of  rotation  as  the  oscillating  matter  rose  and  sunk  in 
level.  Had  gravitation  bound  down  the  enormous  mass, 
drawn  it  with  the  force  of  thousands  of  thousands  tons,  it 
would  have  stood  firm  and  unyielding.  How  much  safer 
for  a  ship  to  float  on  the  free  moving  water,  than  to  re- 
ceive the  shock  of  the  storm  when  stranded  on  the  solid 
rock  ! 

As  we  write,  we  raise  our  eyes  to  a  range  of  lofty  moun- 
tains, the  top  of  one  of  which  rises  some  four  thousand  feet, 
with  a  summit  of  bald  rock,  the  granite  reaching  from  this 
height  to  the  broad  base,  and  extending  for  many  long  miles 
below,  ledge  upon  ledge,  stratum  upon  stratum,  all  bound 
together  by  the  circulation  of  force  through  every  particle, 
fragment,  mass.  But  there  is  no  weight.  The  granite 
crystals  touch  each  other  no  more  closely  at  the  lowest  base 
than  at  the  summit,  nor  press  more  heavily  on  each  other. 
There  is  no  weight,  except  on  the  condition  that  the  mountain 
descends  to  a  level  of  rotation.  It  is  self-poised,  as  is  the 
whole  earth. 

Practical  men,  who  know  only  what  they  have  seen,  and 


108  OUTLINES    OP  A   SYSTEM   OF 

believe  in  what  takes  place,  without  being  troubled  by 
theory,  work  on  the  faith  that  there  is  no  force  of  gravita- 
tion in  the  mass  which  preserves  one  line  of  rotation.  In 
taking  away 'the  foundation  of  a  brick  wall  which  had  been 
undermined,  to  rebuild  it,  the  owner  expressed  his  fears 
that  too  much  had  been  removed  of  the  support  at 
once,  and  that  the  building  would  fall.  The  reply  of  the 
mechanic  was,  "  I  used  to  fear,  but  now  I  know  that  it  is 
safe  until  it  begins  to  move,  and  I  shall  work  without  any 
jar ;  if  it  should  begin  to  move,  twice  the  present  support 
would  not  keep  it  up."  In  taking  away  the  support  of  the 
arch  of  a  stone  bridge,  after  the  keystone  was  put  in,  a 
slight,  sudden  sag  of  the  bridge  crushed  the  keystone,  —  a 
stone,  the  cohesion  of  which,  if  standing  firm  at  one  level, 
would  have  borne  all  the  granite  that  could  have  been  piled 
miles  high  upon  it. 

This  principle  is  evidenced  by  the  superior  security  of  the 
arch  for  bridges  and  similar  structures.  In  the  arch,  there 
can  be  no  descent  without  crushing  the  material  of  which  it 
is  formed.  Thus  too  has  the  passing  of  a  body  of  troops 
over  a  bridge,  with  measured  step  by  beat  of  drum,  often 
given  the  vibration  which  calls  into  action  the  weight  or  force 
of  descent.  In  the  Britannia  tubular  iron  bridge  of  immense 
weight,  some  of  the  spans  of  which  are  four  hundred  and 
seventy-two  feet  in  length,  care  has  been  taken  to  secure 
the  bridge  against  vibration  ;  the  upper  portions  of  the  tube 
are  made  thicker,  operating  as  an  arch,  the  particles  of 
which  are  compressed  by  any  descent.  Heavy  as  it  is,  it 
will  undoubtedly  stand  if  it  has  no  vibration  to  call  forth  the 
force  of  descent. 

The  moon  floating  around  the  earth  will  not  fall  because 
she  possesses  force  for  rotation,  in  proportion  to  her  distance 


MECHANICAL   PHILOSOPHY.  109 

from  the  earth.  So  the  crust  of  the  earth  cannot  fall,  as  it 
ever  has  the  due  force  for  rotation ;  there  may  be  oscilla- 
tion in  the  orbit  of  the  moon,  the  mean  distance  being  pre- 
served ;  there  may  be  a  movement  of  the  earth's  surface,  but 
it  is  an  oscillatory  movement ;  there  is  both  the  rise  and  the 
fall,  one  mean  of  rotation  being  preserved.  Masses  and  frag- 
ments of  the  earth  fall,  when  unsupported  they  take  a  lower 
level  of  rotation,  and  as  they  fall  yield  up  to  other  bodies 
the  force  of  their  former  superior  level.  Hence  every 
movement  is  oscillatory,  the  transfer  of  force,  —  the  force 
remaining  of  fixed  quantity  in  all  its  transfers,  preserving 
the  perfect  equilibrium  of  creation. 

After  the  assertion  of  the  law  of  falling  bodies  by  Galileo, 
there  was  found  a  great  difficulty  in  applying  it  to  the 
commencement  of  the  motion  ;  for  this  beginning  of  motion 
clearly  shows  that  they  do  not  fall  by  attraction.  Great 
disputes  took  place  in  regard  to  the  velocity  with  which 
bodies  begin  to  fall.  It  led  to  the  consideration  of  the  infinite 
divisibility  of  space  ;  for  the  motion  at  its  commencement  is 
so  slight  that  the  body  hardly  appears  to  move,  or,  as  it  has 
been  expressed,  "  when  a  body  begins  to  fall  from  rest,  it 
begins  to  fall  with  no  velocity.  In  one  thousandth  part  of 
a  second  it  has  only  acquired  one  thousandth  part  of  the 
velocity  which  it  has  at  the  end  of  one  second."  If  gravi- 
tation act  with  its  supposed  force  upon  a  body  at  rest,  how 
great  would  be  its  instantaneous  velocity  when  the  support 
was  taken  away  !  Its  fall  would  be  as  sudden  as  the  recoil 
of  a  bent  spring. 

Nor  could  it  be  understood  why  bodies  which  had  fallen 
by  the  force  of  gravity  should  be  able  to  rise  again  to  the 
same  level  against  the  force  'of  gravity ;  or  why  on  the 
inclined  plane  the  velocity  of  a  body  should  be  measured  by 

10 


110  OUTLINES    OF   A   SYSTEM    OP 

the  vertical  height  from  which  it  falls ;  nor  why  the  fall 
should  be  with  uniformly  accelerated  velocity.  Even  Gal- 
ileo, vigorous  as  were  his  powers  of  thought,  could  not  mas- 
ter the  subject.  And  the  obscurity  has  continued  to  this 
day. 

The  theory  of  gravitation  acknowledges  a  difference  be- 
tween the  weight  of  a  body,  that  is,  its  tendency  to  fall, 
and  the  force  of  the  fall,  —  weight  being  an  invariable  quality, 
while  the  force  of  descent  is  in  proportion  to  the  time  of  the 
fall.  We  rega'rd  the  cause  of  the  fall,  and  the  force  given  out 
by  the  fall  as  essentially  different,  and  we  hope  that  we  shall 
be  able,  in  the  process  of  this  inquiry,  to  explain  the  cause 
as  well  as  the  results.  But  whatever  it  may  be,  the  stone 
unsupported  will  not  remain  at  rest.  We  have  just  read  in 
an  account  of  a  recent  ascent  of  Mont  Blanc,  that  "  spots 
have  to  be  passed  where  no  word  can  be  spoken  lest  thou- 
sands of  tons  of  snow  should  be  set  in  motion  ;  "  for  it  has 
been  known,  that  the  mere  vibration  of  the  air,  caused  by 
the  human  voice,  has  brought  down  the  avalanche.  The 
intensity  of  molecular  action,  the  pulse  of  nature,  the  very 
throb  of  force,  the  vibration  and  oscillation  of  all  things 
would  account  for  the  fact  that  the  suspended  body  has 
motion,  has  the  beginning  of  its  downward  course.  The 
impulse  given,  the  most  minute  line  of  descent  induced, 
there  is  the  spare  force  of  rotation,  there  is  force  for  the 
motion  of  the  mass  in  a  new  direction.  It  has  commenced 
its  fall,  —  it  has  unused  force.  It  cannot  rotate  more  rapidly 
at  the  lower  level ;  for  it  is  a  part  of  a  current  of  matter 
passing  round  the  earth  in  an  equable  stream.  *  Downward, 
then,  it  must  take  its  way.  Its  very  appearance  in  the 
act  of  falling  indicates  the  law  of  its  motion.  It  is  not  at- 
tracted ;  for  it  does  not  rush  at  once  to  the  earth,  as  do  the 


MECHANICAL    PHILOSOPHY.  Ill 

particles  of  steel  to  the  magnet ;  but,  for  an  instant,  as  if  in 
suspense,  like 

"  A  long-swept  wave  about  to  break, 
It  on  the  curl  hangs  pausing ;  " 

then,  gathering  force  for  its  downward  career,  it  falls ; 

"  Still  gathering  force  it  smokes,  and  urged  amain, 
Whirls,  leaps,  and  thunders  down,  impetuous  to  the  plain." 

The  force  obtained  by  the  change  of  the  level  of  the  falling 
mass, — of  water  for  instance,  —  cannot  come  from  the  at- 
tracting earth ;  for  the  attractive  force  is  force  to  draw  the 
mass  toward  her  centre,  and  having  acted  according  to  this, 
the  essential  principle  of  attraction,  it  would  cease  to  act,  or 
merely  hold  the  water  at  its  new  level.  But  the  force  of 
the  fall  of  bodies  remains  ;  it  is  a  living  principle.  It  was 
in  them  at  their  higher  level,  there  acting  in  rotation.  If 
water  falls,  it  transfers  this  force  to  other  bodies,  inducing 
motion  in  them.  If  not  imparted,  it  is  sufficient  in  intensity 
to  raise  the  water  again  to  its  former  level.  It  is  not  a 
mere  gravitating,  or  downward  force,  but  force  giving  motion 
irrespective  of  direction. 

Thus,  the  fall  of  water  over  an  artificial  dam  is  not  from 
the  downward  attraction  of  the  earth.  That  force  can  only 
exert  its  essential  property  of  bringing  the  particles  of  mat- 
ter nearer  to  each  other.  In  doing  this,  it  has  discharged 
its  only  conceivable  function.  But  the  particles  of  water 
by  the  act  of  descent  impart  the  spare  force  of  their  lower 
level  of  rotation;  and  this  force,  diverted  from  the  majestic 
stream  of  rotative  power,  can  have  given  to  it  by  mechanical 
appliances  the  line  of  direction  which  crushes  the  grain,  or 
on  the  revolving  spindle  twirls  the  fibre  of  cotton,  —  the 
mechanic  using  the  force  of  nature  for  the  comforts  and 


112 

luxuries  of  life.  Thus  is  imparted  to  the  practical  mechanic 
a  dignity  arising  from  his  position.  He  is  not  a  mere  cun- 
ning workman  in  wood  and  brass ;  but  he  bears  in  his  hand 
the  sceptre  of  power  over  nature,  —  he  controls  her  ener- 
gies, — he  borrows  her  force, — from  water,  wind,  and  steam, 
and  through  the  lever  and  the  wheel,  he  directs  the  action  of 
this  force  for  the  well-being  of  man. 

When  engaged  in  the  examination  of  facts,  the  thoughts 
will  oscillate  from  them  to  abstract  principles,  —  from 
material  things  to  that  which  they  represent.  Does  not 
this  law  of  the  mind  prove  that  the  connection  of  the  intel- 
lect with  material  objects  is  not  its  only  tie  to  the  universe  ? 
We  have  considered  the  artisan  as  borrowing  the  power 
of  nature  for  his  purposes,  —  considered  him  as  not  confined 
to  that  degree  of  strength  only  which  flows  through  his  own 
frame ;  he  goes  out  of  himself  to  the  great  fountains  of 
energy  for  his  purposes.  So,  he  who  would  comprehend  the 
things  around  him, — he  who  is  the  artisan  in  philosophy, — 
is  he  confined  to  his  own  feeble  strength,  limited  to  his  own 
power  of  thought  ?  Is  there  not  a  communion  between  him 
and  truth  more  direct  than  comes  from  the  contemplation  of 
external  objects  merely  ?  Is  he  never  allowed  to  borrow 
wisdom  from  the  Fountain  of  Wisdom  ? 

"  Now  all  the  knowledge  and  wisdom  that  is  in  creatures, 
whether  angels  or  men,  is  nothing  else  but  a  participation 
of  that  one  eternal,  immutable,  and  uncreated  wisdom  of 
God,  or  several  signatures  of  that  one  archetypal  seal,  or 
like  so  many  multiplied  reflections  of  one  and  the  same  face, 
made  in  several  glasses,  whereof  some  are  clearer,  some 
obscurer,  some  standing  nearer,  some  further  off." 


CHAPTER  VI. 


"  SURELY  IT  IS  A  WORK  WELL  DESERVING  OUR  PAINS,  TO  MAKE  A  STRICT 
INQUIRY  CONCERNING  THE  FIRST  PRINCIPLES  OF  HUMAN  KNOWLEDGE, 
TO  SIFT  AND  EXAMINE  THEM  ON  ALL  SIDES  ;  ESPECIALLY  SINCE  THERE 
MAY  BE  SOME  GROUNDS  TO  SUSPECT,  THAT  THESE  LETS  AND  DIFFI- 
CULTIES, WHICH  STAY  AND  EMBARRASS  THE  MIND  IN  ITS  SEARCH 
AFTER  TRUTH,  DO  NOT  SPRING  FROM  ANY  DARKNESS  AND  INTRICACY 
IN  THE  OBJECTS,  OR  NATURAL  DEFECT  IN  THE  UNDERSTANDING,  SO 
MUCH  AS  FROM  FALSE  PRINCIPLES  WHICH  HAVE  BEEN  INSISTED  ON, 
AND  MIGHT  HAVE  BEEN  AVOIDED. 

"  HOW  DIFFICULT  AND  DISCOURAGING  SOEVER  THIS  STEP  MAY  SEEM, 
WHEN  I  CONSIDER  HOW  MANY  GREAT  AND  EXTRAORDINARY  MEN  HAVE 
GONE  BEFORE  ME  IN  THE  SAME  DESIGN,  YET  I  AM  NOT  WITHOUT  SOME 
HOPES,  UPON  THE  CONSIDERATION  THAT  THE  LARGEST  VIEWS  ARE  NOT 
ALWAYS  THE  CLEAREST,  AND  THAT  HE  WHO  IS  SHORT-SIGHTED  WILL 
BE  OBLIGED  TO  DRAW  THE  OBJECT  NEARER,  AND  MAY  PERHAPS,  BY  A 
CLOSE  AND  NARROW  SURVEY,  DISCERN  THAT  WHICH  HAD  ESCAPED 

FAR  BETTER  EYES."  —  Bishop  Berkeley. 

THERE  are,  unquestionably,  two  different  casts  of  mind,  — 
one  giving  greater,  the  other  less  attention  to  facts  ;  the 
one  the  more  rigid  and  exact  in  observation,  the  other 
the  more  prone  to  speculation.  Hence  the  perpetual  con- 
flict between  what  are  called  the  practical  and  the  theoret- 
ical. But  the  dispute  concerning  the  values  of  the  two 
methods  in  philosophy  is  in  words  merely.  The  man  who 
only  knows  facts,  and  the  man  who,  ignorant  of  the  doings 
of  nature,  dreams  rather  than  judges,  are  both  unfit  for 
philosophy.  Theories  unsupported  by  facts  are  worthless, 
and  an  accumulation  of  facts  without  reference  to  the  laws 
of  their  combination  is  also  worthless. 
10* 


114  OUTLINES    OF   A    SYSTEM   OF 

But  every  man  is  in  some  degree  a  theorist,  and  he 
is  a  theorist  because  he  is  a  man.  The  animal  alone 
rests  contented  with  the  facts  presented  to  the  senses.  In 
proportion  to  the  strength  of  a  mind  is  its  tendency  to 
go  beneath  the  surface  of  things,  to  be  dissatisfied  with- 
out hypothesis  to  connect  the  facts  that  are  observed, 
and  therefore  to  seek  some  principle  of  unity.  Thus  every 
philosopher  is  necessarily  a  theorist.  Even  Bacon,  the 
father  of  the  Inductive  Method,  was  a  theorist,  and  at  times 
a  wild  and  fanciful  theorist.  "  Some  noises,"  says  he, 
"  help  sleep,  as  the  blowing  of  the  wind  and  the  trickling  of 
the  water ;  they  move  a  gentle  attention,  and  whatever 
moveth  attention  without  too  much  labor,  stilleth  the  natural 
and  discursive  motion  of  the  spirits."  "  What  indeed," 
asks  a  profound  and  accurate  thinker,  "  are  Newton's  Que- 
ries but  so  many  hypotheses  which  are  proposed  to  philoso- 
phers as  subjects  of  examination  ?  "  "  And,"  he  continues, 
"  did  not  even  the  great  doctrine  of  gravitation  take  its  first 
rise  from  a  fortunate  conjecture  ?  " 

It  is  remarked  by  Sir  David  Brewster  that  "  the  influ- 
ence of  the  imagination  as  an  instrument  of  research  has 
been  much  overlooked  by  those  who  have  ventured  to  give 
laws  to  philosophy.  This  faculty  is  of  the  greatest  value  in 
physical  inquiries  ;  if  we  use  it  as  a  guide  and  confide  in  its 
indications,  it  will  infallibly  deceive  us  ;  but  if  we  employ  it 
as  an  auxiliary,  it  will  afford  us  the  most  invaluable  aid." 
After  an  hypothesis  has  been  suggested  by  the  imagination, 
it  should  become  the  subject  of  rigorous  examination,  and  be 
retained  or  discharged,  as  it  may  or  may  not  give  the  desired 
explanation  ;  for  the  proof  of  the  truth  of  a  theory  is  its  har- 
mony with  facts.  True  philosophy,  therefore,  uses  both 
reason  and  observation  in  making  progress. 


MECHANICAL  PHILOSOPHY.  115 

And  while  philosophy  demands  that  no  theory  shall  be 
admitted  as  proved  any  further  than  it  is  supported  by  facts, 
and  that  science  should  be  guarded  from  wayward  fancies 
and  day-dreams,  equal  care  should  be  taken  to  reexamine 
the  theories  that  are  current,  so  that  the  errors  that  must 
necessarily  be  handed  down  in  the  regular  transmission  of 
science,  from  the  education  of  one  generation  by  the  pre- 
ceding, may  be  expelled.  There  is  far  less  danger  that 
new  errors  be  received  than  that  old  ones  be  suffered  to  re- 
main ;  for  against  new  theories  the  educated  contend  most 
strenuously,  if  they  conflict  with  a  system  to  the  full  com- 
prehension of  which  a  lifetime  has  been  devoted.  Errors 
once  established  therefore  become  permanent ;  they  are 
incorporated  into  a  system.  Common  sense,  which  might 
detect  them,  defers  to  the  authority  of  science,  and  science 
to  the  wisdom  of  former  times.  However,  all  things  on  the 
whole  are  wisely  determined  so  that  progress  shall  be  made, 
though  it  be  by  a  succession  of  waves  surging  at  long  inter- 
vals, rather  than  by  the  steady  advance  of  the  tide.  But 
we  have  been  drawn  from  our  path.  We  return  to  the  exam- 
ination of  the  theories  relating  to  the  differing  densities  of 
the  atmosphere,  as  indicated  by  the  rise  and  fall  of  the 
mercury  in  the  barometer. 

It  is  generally  supposed  that  the  atmosphere  increases  in 
density  from  its  upper  surface  to  its  line  of  contact  with  the 
globe.  In  the  language  of  Sir  John  Herschell,  "  when  we 
have  ascended  to  the  height  of  one  thousand  feet,  we  have 
have  left  below  us  about  one-thirtieth  of  the  atmosphere  ;  at 
ten  thousand  six  hundred  feet  of  elevation,  rather  less  than 
that  of  JEtna,  we  have  ascended  through  about  one  third  ; 
at  eighteen  thousand  feet,  which  is  nearly  that  of  Cotopaxi, 
through  one  half  of  the  material,  or  at  least  of  the  pondera- 


116  OUTLINES   OF  A   SYSTEM   OF 

ble  body  of  air  incumbent  on  the  earth's  surface."  This 
lessening  density  as  we  go  up  from  the  surface,  is  supposed 
to  be  proved  by  the  depression  of  the  mercury  in  the 
barometrical  tube. 

Before  the  experiments  of  Torricelli,  the  ascent  and  sup- 
port of  fluids  by  a  vacuum  were  accounted  for  by  the  abhor- 
rence of  nature  for  a  vacuum.  When  it  was  discovered 
that  this  "abhorrence"  was  limited  for  water  to  about 
thirty-three  feet,  for  mercury  to  about  thirty  inches,  and 
for  other  fluids  in  proportion  to  their  density,  some  new 
theory  became  necessary,  and  the  weight  or  pressure  of  the 
atmosphere  was  substituted.  Galileo,  Torricelli,  Pascal, 
seem  jointly  to  have  formed  the  new  theory,  and  Pascal 
fully  established  it  by  experiments,  which  gave  the  fact  that 
at  different  altitudes  the  level  of  the  mercury  varied,  —  that 
it  rose  higher  in  the  vacuum  as  the  level  of  the  instrument 
decreased,  and  that  it  fell  as  the  barometer  was  elevated. 

Thus  the  "fuga  vacui"  being  abandoned,  the  support  of 
the  fluid  being  attributed  to  the  pressure  of  the  atmosphere, 
and  the  degree  of  support  being  found  to  lessen  upon  ascent, 
the  hypothesis  that  the  weight  or  pressure  of  the  atmosphere 
decreases  according  to  elevation  was  established,  and  re- 
mains unquestioned  to  this  day.  This  theory,  however, 
though  it  has  been  useful  for  many  practical  purposes,  does 
not  give  a  complete  explanation  of  the  facts  connected  with 
the  barometer. 

How  is  the  air  supposed  to  be  packed  according  to  baro- 
metrical indications  ?  We  will  quote  from  one  who  very 
distinctly  gives  the  commonly  received  opinions.  "  The 
first  stratum  of  air  gravitates  with  its  own  share  of  the 
earth's  attraction,  the  second  with  its  own  share,  and  with 
the  weight  of  the  stratum  over  it,  and  so  on ;  the  lower 


MECHANICAL    PHILOSOPHY.  117 

stratum  bearing  in  addition  to  its  own  weight  all  the  weight 
of  the  air  over  it."  The  atmosphere  has  also  been  com- 
pared to  a  series  of  fleeces  of  wool,  the  lower  the  most 
compressed. 

Gravitation  of  the  atmosphere,  if  the  air  be  attracted  at 
all,  would  appear  at  first  sight  as  if  threads  were  attached 
to  each  particle,  drawing  every  one  with  equal  tension.  No 
particle  could  rise  relatively  to  another  particle,  if  all  were 
drawn  down  with  equal  force.  The  particle  going  down 
must  be  more  strongly  drawn,  the  particle  going  up  must 
be  drawn  with  less  comparative  force.  With  equal  attract- 
ion there  could  be  no  relative  change  of  place.  The  only 
difference  in  weight  of  the  different  strata  would  arise  from 
the  increase  or  diminution  of  the  force  of  attraction,  accord- 
ing to  the  distance  of  each  stratum  from  the  centre  of 
attraction.  If  this  force  acted  on  the  whole  atmosphere  as 
one  volume,  the  whole  volume  would  be  of  as  uniform  den- 
sity as  a  mass  of  granite.  If  the  force  of  attraction  operated 
on  each  particle  according  to  its  distance  from  the  centre  of 
attraction,  the  difference  in  the  weight  qf  different  strata 
would  be  far  less,  than  that  apparently  indicated  by  the 
barometer. 

Such  a  condensation  of  the  atmosphere  as  is  supposed 
could  not  result  from  the  law  of  gravitation ;  for  that  law 
assumes  a  decrease  of  force  proportional  to  the  square  of 
the  distance.  A  volume  of  one  hundred  cubic  inches  of  air 
weighs  but  thirty-one  grains,  —  is  attracted  by  a  force  the 
value  of  which  is  only  thirty-one  grains.  How  large  must 
be  the  volume  of  air  which  weighs  a  ton, — is  attracted  by  a 
force  measured  by  one  ton  ?  It  would  cover  the  whole  of  a 
large  and  high  mountain.  This  ton  of  air  would  weigh  but 
one  ounce  less,  a  mile  from  the  surface  of  the  globe,  than  it 


118  OUTLINES    OF   A   SYSTEM   OF 

would  at  its  very  surface.  This  is  the  only  ratio  in  which 
gravitation  could  change  the  weight  of  the  different  strata 
of  air.  The  earth  can  have  no  favoritism.  She  holds  in 
place  or  draws  down  every  particle  of  air  equally,  —  or, 
more  accurately,  in  proportion  to  its  distance  from  the 
centre. 

But,  admitting  that  each  stratum  of  air  bears  not  only  its 
own  share  of  the  earth's  attraction,  but  also  the  weight  of 
all  the  strata  over  it,  still  this  could  not  condense  the  atmo- 
sphere to  the  degree  that  is  supposed. 

No  one  doubts  that  the  temperature  of  the  atmosphere 
changes  with  its  level.  At  the  summit  of  a  mountain,  where 
by  theory  the  air  has  lost  one  half  of  its  density,  the  cold 
compared  with  that  at  the  surface  of  the  earth  below  is 
most  intense.  Heat,  it  is  said,  always  rarefies  the  air,  cold 
condenses  it ;  and  of  course  there  would,  from  this  cause, 
be  a  greater  density  in  proportion  to  the  elevation. 

It  is  also  settled,  that  the  force  of  the  elasticity  of  air 
increases  with  its  density.  Of  course  elasticity  acts  against 
the  rarer  strata,  and  this  elasticity  would  of  itself  pre- 
serve throughout  the  whole  atmosphere  an  equilibrium  of 
density.  If  a  quantity  of  air  be  artificially  condensed,  how 
quickly  will  it  return  to  its  normal  state  when  the  force 
which  compresses  it  is  removed  !  If  the  air  be  an  elastic 
fluid,  no  volume  of  it  can  exist  without  an  equal  pressure  in 
every  direction,  —  be  the  volume  large  or  small,  a  few  cubic 
inches  or  the  whole  atmosphere.  If  any  portion  of  it  be 
rarefied  by  heat,  this  will  give  to  its  particles  greater  <c  force 
of  repulsion,"  so  as  to  equalize  its  pressure  with  that  of  the 
surrounding  denser  air. 

Moreover,  if  gravitation  could  press  down  the  different 
strata  of  the  air  in  the  ratio  supposed,  it  could  not  maintain 


MECHANICAL   PHILOSOPHY.  119 

the  pressure,  —  it  could  not  preserve  this  difference  of  den- 
sity. There  is  a  perfect  intermobility  of  the  particles  of 
fluids,  and  every  wind  that  blows  would  tend  to  bring  back 
the  equilibrium.  It  is  supposed  that  winds  are  caused  by  the 
rushing  of  air  from  the  colder  and  more  condensed  portions 
of  the  atmosphere  to  those  comparatively  more  rarefied. 
An  upward  current  would  at  once  be  established  to  restore 
an  equilibrium,  —  to  undo  what  gravitation  had  done. 

But  the  law  by  which  the  atmosphere  is  packed  ac- 
cording to  barometrical  indications,  is  not  the  law  which 
regulates  the  gravitation  of  fluids.  It  is  a  law  which  acts 
in  this  case  only.  The  law,  by  which  one  stratum  of  the 
atmosphere  bears  not  only  its  own  weight,  but  that  of  all  the 
strata  over  it,  is  assumed  for  special  purposes.  Having  dis- 
charged its  function,  it  is,  ever  after,  a  dead  letter.  We 
hear  no  more  of  this  vertical  gravitation,  —  no  more  of  the 
bearing  down  of  one  stratum  upon  another.  Fluids  press 
equally  in  all  directions.  This  is  acknowledged  as  a  general 
law.  The  very  action  of  the  atmosphere  on  the  barometer 
must  ofcen  be  by  an  upward  gravitating  power,  pressing 
against  the  leather  at  the  bottom  of  the  cistern  containing 
the  mercury. 

The  acknowledged  principle  that  the  pressure  of  fluids  is 
equal  in  all  directions,  "  upwards,  downwards,  and  side- 
ways," would  prevent  such  a  compression  of  the  atmosphere 
as  the  barometer  is  supposed  to  indicate.  If  a  cubic  foot  of 
air  presses  equally  by  its  six  sides,  it  presses  the  cubic  foot 
above  it  with  the  same  force  as  the  cubic  foot  below  it.  In 
no  way  whatever  can  it  be  shown,  without  contradicting  all 
the  present  theories,  that  there  is  a  difference  of  density 
among  the  different  strata  of  air.  If  this  difference  actually 
exists,  we  must  give  up  gravitation  with  force  according  to  dis- 


120  OUTLINES    OF   A    SYSTEM   OF 

tance,  the  action  of  heat  in  the  rarefaction  of  the  air,  the 
elasticity  of  air  in  proportion  to  its  density ,  the  diffusiveness 
of  air,  the  intermobility  of  the  particles  of  air,  and  the  prin- 
ciple that  the  pressure  of  fluids  is  equal  in  every  direction. 

But  in  fact  the  varying  density  of  the  air  has  no  proof 
whatever.  It  may  be,  or  may  not  be.  If  it  be,  it  is  caused 
by  a  principle  not  embraced  in  any  of  the  present  theories, 
and  it  cannot  be  proved  from  the  range  of  the  mercurial 
column.  We  wish  to  express  this  idea  distinctly.  If  the 
air  be  more  dense  at  the  surface  of  the  earth  than  a 
mile  above  it,  the  increase  of  density  does  not  arise  from 
gravitation  ;  and,  if  there  is  a  difference  of  density  at  differ- 
ent levels,  the  barometer  cannot  indicate  it. 

We  referred,  in  the  preceding  chapter,  to  the  oscillations 
of  the  mercury  at  one  supposed  level ;  we  have  occasion  to 
use  again  the  same  facts,  and  to  add  to  them  others  of  the 
same  character. 

These  oscillations,  of  which  the  range  is  about  three 
inches,  while  the  barometer  remains  at  the  same  place  on 
the  earth's  surface,  are  not  accounted  for  by  the  present 
philosophy.  Scientific  men  confess  their  inability  to  explain 
them.  Professor  Daniell  says,  "  The  cause  of  these  oscilla- 
tions has  long  been  the  subject  of  investigation  with  philos- 
ophers, and  the  problem  in  all  its  generalities  is  difficult  and 
complicated."  "  The  difficulty,"  says  an  article  in  the 
London  Encyclopedia,  "  consists  in  explaining  why  these 
oscillations  are  greater  in  high  latitudes  than  between  the 
tropics,  as  well  as  why  they  should  exceed  in  all  cases  the 
quantities  which  calculation  of  different  densities  of  atmo- 
sphere might  assign."  Again :  "  It  is  hard  to  say  what  can 
be  the  cause  of  the  changes  of  the  height  of  the  mercury  at 
the  same  level,  —  changes  which  would  be  equal  to  a  change 
of  level  of  two  or  three  thousand  feet." 


MECHANICAL    PHILOSOPHY.  121 

Ifc  is  supposed  by  some  that  different  degrees  of  hu- 
midity in  the  atmosphere  might  account  for  these  changes. 
Professor  Leslie  inclines  to  this  belief,  "  because  all  other 
assigned  causes  are  insufficient."  But  the  barometer  usually 
falls  in  a  damp  atmosphere,  and  vapor  of  itself  has  weight, 
nor  does  it  necessarily  rarefy  air  which  contains  it.  The 
winds  passing  over  the  surface  of  the  earth  cannot  be  the 
cause  ;  for,  as  we  have  already  shown,  it  would  require  a  wind 
passing  over  nearly  three  thousand  miles  at  the  rate  of  sixty 
miles  an  hour,  to  change  the  height  of  the  mercury  half  an 
inch.  Attempts  have  also  been  made  to  trace  the  cause  in 
the  vacua  occasioned  by  conflicting  winds.  In  vain  ;  for 
winds  by  theory  restore  equilibrium,  —  they  do  not  create 
inequalities,  nor  could  a  vacuum  exist  for  days  and  weeks 
if  it  could  be  formed. 

The  maximum  of  oscillation  is  near  the  parallel  of  45° 
latitude.  The  oscillations  vary  with  the  time  of  the  year, 
(being  greater  in  one  month,  less  in  another  month,)  and  also 
with  the  hour  of  the  day.  They  also  vary  with  sudden 
changes  of  the  level  of  the  water,  with  the  height  of  the 
tides,  and  with  the  position  of  the  moon  in  relation  to  the 
earth.  All  these  periodic  and  other  changes  cannot  be 
traced  to  the  state  of  the  atmosphere  as  the  cause.  There- 
fore, if  the  barometer  indicates  varying  density  of  the  atmos- 
phere, it  also  indicates  some  other  fact,  —  the  oscillations 
have  some  other  cause.  If  it  do  not  indicate  the  density  of 
the  air  in  one  position  on  the  earth,  it  may  not  in  any,  espe- 
cially as  the  corresponding  variation  of  density  has  no  proof 
independent  of  the  change  in  the  mercurial  column. 

But  it  may  be  thought  that  we  have  forgotten  the  fact  that, 
"  if  a  man  ascends  a  high  mountain,  he  will  feel  an  incon- 
venience in  his  ears,  and  other  cavities  of  the  body  from  the 
11 


122  OUTLINES    0¥   A   SYSTEM   OP 

dilatation  of  the  enclosed  air  adjusting  itself  to  the  dimin- 
ished outside  pressure."  This /act,  if  it  be  true,  is  insuffi- 
cient to  bear  the  burden  of  proof  of  the  great  principle  under 
discussion.  If  uncomfortable  bodily  sensations  are  experi- 
enced, it  does  not  follow  that  the  reason  for  them  is  the 
"  dilatation  of  the  inclosed  air,"  or  the  rarefaction  of  that 
outside.  There  may  be  other  reasons  for  painful  sensations 
on  the  ascent  of  high  mountains. 

The  effect  on  the  animal  structure  of  the  air  at  great 
heights,  we  think,  proves  distinctly  that  it  is  not  so  rarefied 
as  is  supposed.  The  bird  soars  as  lightly  from  the  top  of 
the  high  mountain  as  from  the  plain.  The  condor,  the 
heaviest  of  birds,  flies  without  effort  at  a  height  of  fifteen 
thousand  feet,  though  supported  by  air  of  only  half  the 
density  of  that  below.  And  man,  after  recovering  from  the 
fatigue  of  ascent,  is  not  always  distressed  for  breath ;  he 
does  not  require  lungs  of  double  capacity,  nor  does  he 
breathe  twice  as  fast  to  obtain  his  usual  supply  of  vital  air. 
No  one  could  live  comfortably  in  air  of  only  half  its  usual 
density ;  yet  in  the  highest  ascents  in  balloons  we  read 
that  "  the  aeronauts  suffered  no  inconvenience  in  their  respir- 
ation or  other  animal  functions."  We  shall  again  recur  to 
this  part  of  the  subject. 

It  may  also  be  alleged  that  the  boiling  point  of  water 
varies  according  to  elevation,  because  the  pressure  upon  the 
surface  of  the  water  is  diminished  by  the  rarefaction  of  the 
air ;  or  that,  as  water  boils  in  vacuo  at  a  very  low  tempera- 
ture, so  as  we  ascend  and  the  air  is  rarefied,  water  boils  with 
a  less  degree  of  heat.  The  reason  why  water  boils  more 
easily  the  greater  its  elevation,  is  simply  its  possession  of  a 
rotative  force  proportional  to  its  level  of  rotation.  Beyond 
a  certain  elevation  water  would  at  once  pass  into  vapor. 


MECHANICAL    PHILOSOPHY. 

We  do  not  expect  the  minds  of  others,  at  this  period  of 
the  investigation,  to  accept  pur  explanation  of  the  vaporiza- 
tion of  water  at  different  levels.  We  will,  therefore,  for 
the  present,  admit  that  the  atmosphere  is  more  or  less  rare- 
fied according  to  the  altitude  of  its  strata,  —  that  the  mean 
weight  of  the  air,  from  the  action  of  heat  or  other  causes, 
varies,  so  as  to  make  a  column  of  it  bear  on  the  earth  some- 
times with  a  greater,  sometimes  with  a  lesser  pressure. 
But  even  if  we  admit  the  gravitation  of  air,  and  the  varying 
weight  of  a  given  quantity  of  air,  it  does  not  follow  that 
either  its  normal  pressure  or  its  variation  of  pressure  is 
measured  by  the  stationary  or  varying  weight  of  the  sus- 
pended column  of  mercury.  In  other  words,  there  is  no 
proof  that  the  weight  of  the  column  of  mercury  is  the 
measure  of  the  weight  of  the  air. 

In  the  first  place,  when  the  barometer  is  constructed,  the 
mercury  in  the  tube  does  not  owe  its  elevation  to  the  press- 
ure of  the  air.  Let  a  tube  closed  at  the  top  be  immersed 
in  mercury,  and  when  filled  let  it  be  withdrawn  upward  by 
the  hand  ;  the  mercury  is  raised  with  the  tube  above  the 
level  of  the  mercury  from  which  it  is  taken.  The  force  re- 
quired to  lift  it  is  just  the  weight  of  the  mercury  and  tube 
together.  The  pressure  of  the  atmosphere  on  the  lower 
surface  of  mercury  does  not  in  tae  least  degree  aid  in  the 
elevation,  does  not  diminish  the  weight,  —  because  the  sus- 
taining mercury  is  pressed  by  the  air,  not  one  iota  less  of 
force  is  required  to  give  the  sustained  mercury  its  eleva- 
tion. The  fact  is  admitted,  and  is  accounted  for  in  this 
manner :  — "  The  force  used  in  lifting  the  mercury  is 
needed  to  elevate  the  air  over  the  tube  ;  that  being  done  by 
the  applied  force,  it  is  the  weight  of  the  atmosphere  which 
elevates  the  mercury  in  the  tube."  But  this  reason  is 


124  OUTLINES    OF   A    SYSTEM    OF 

given  without  reflection  ;  for  the  air  is  no  heavier  over  the 
tube  when  the  tube  is  filled  with  mercury  than  when  it  is 
filled  with  water  or  air,  yet  the  force  applied  measures  the 
weight  of  the  fluid  within,  and  the  contained  weight  does 
not  increase  or  diminish  the  weight  of  the  column  of  air 
over  the  tube.  It  is  certain,  therefore,  that  when  the 
column  of  mercury  is  lifted  with  the  tube,  it  is  the  applied 
force  that  lifts  it,  and  not  the  weight  of  the  atmosphere 
bearing  on  the  surface  of  the  mercury  from  which  it  is 
withdrawn.  Of  course,  the  weight  of  the  atmosphere,  not 
capable  in  the  least  of  aiding  the  process  of  elevation,  has 
no  efficacy  in  sustaining  the  column  wrhen  raised.  One 
would  almost  suppose  that  an  air-supported  column  of  mer- 
cury would  be  like  the  air-supported  balloon,  and  would  not 
press  with  any  weight  upon  the  instrument. 

When  the  tube  is  elevated  beyond  what  may  be  termed 
the  limit  of  extension,  the  mercury  is  no  longer  lifted  with 
it.  However  high  the  tube  be  drawn,  the  surface  of  the 
mercury  in  it  remains  at  a  certain  distance  from  the  surface 
of  the  lower  mercury.  This  distance,  at  the  mean  level  of 
the  earth's  surface,  is  about  thirty  inches.  It  varies  accord- 
ing to  altitude. 

In  the  usual  process  of  constructing  barometers,  the  tube 
is  filled  with  mercury,  and  its  lower  end  immersed  in  a 
basin  of  the  same  fluid,  technically  called  the  cistern.  The 
mercury  falls  from  the  top  of  the  tube  to  the  limit  of  its 
suspension  ;  and  as  much  as  falls  from  the  tube  is  raised  in 
the  cistern.  As  much  mercury  is  elevated  in  the  cistern  as 
is  depressed  in  the  tube  ;  the  descent  and  ascent  are  exactly 
equal.  In  all  subsequent  changes  the  fall  of  mercury  is 
equal  to  the  rise,  particle  for  particle ;  the  flow  of  mercury 
back  and  forth  makes  the  same  relative  change  in  the 


MECHANICAL    PHILOSOPHY.  125 

volumes  of  the  tube  and  cistern  mercury.  A  perfect  equi- 
librium was  at  first  established  by  the  ascent  of  a  quantity 
of  mercury  in  the  cistern  exactly  equal  in  amount  to  that 
which  descended  in  the  tube,  and  the  equilibrium  is  ever 
sustained  by  the  same  process,  without  reference  to  atmo- 
spheric pressure. 

With  this  perfectly  balanced  instrument  the  atmosphere 
is  supposed  to  be  weighed.  It  is  in  one  scale,  but  no  test 
weight  is  put  in  the  other  scale.  The  air  is  weighed 
against  nothing.  All  the  ponderable  matter  hangs  on  one 
arm  of  an  evenly  balanced  lever,  and  its  weight  is  to  be 
ascertained  by  the  degree  of  the  ascent  of  the  other  arm. 
Place  on  the  outer  mercury  an  additional  pound  of  the 
fluid,  the  mercury  in  the  tube  will  not  rise  so  as  to  weigh  a 
pound  more ;  add  to  the  density  of  the  air  over  the  outer 
mercury,  the  rise  in  the  tube  will  not  correspond  to  the 
increased  weight  of  air  on  or  over  the  cistern.  When  we 
added  mercury  to  that  in  the  cistern,  the  mercury  in  the 
tube  rose  just  enough  to  maintain  its  former  distance  from 
the  lower  surface.  When  the  tube  was  first  plunged  in  the 
cistern,  it  made  no  difference  how  great  or  how  little  was  the 
quantity  of  mercury  in  the  cistern ;  it  makes  no  difference 
afterwards  whether  mercury  be  added  or  taken  away  ;  the 
same  distance  will  be  preserved  between  the  two  surfaces. 
The  rise  of  the  fluid  in  the  tube  will  not,  therefore,  measure 
the  weight  in  and  on  the  cistern. 

It  will  be  said,  however,  that  though,  when  an  additional 
pound  of  mercury  is  placed  in  the  cistern,  an  equivalent 
pound  does  not  rise  in  the  tube,  enough  rises  inside  to  cor- 
respond with  the  increased  height  outside,  and  therefore  it 
weighs  a  column  of  mercury  resting  on  the  surface  of  the 
outside  mercury,  which  is  of  the  same  area  as  itself,  and 


126  OUTLINES    OF   A    SYSTEM    OP 

consequently,  in  weighing  the  air  over  the  cistern,  it  weighs 
a  column  of  air  of  its  own  area  only. 

This  idea  is  a  mere  statement  of  facts.  The  result 
empirically  obtained  is  exalted  into  a  principle,  and  one 
which  is  at  variance  with  all  other  principles  of  the  action 
of  fluids.  Fill  a  cylinder  with  mercury,  and  from  the  cylin- 
der let  a  long  tube  ascend;  subject  the  mercury  in  the 
cylinder  to  the  pressure  of  a  piston,  and  the  rise  of  the  mer- 
cury in  this  tube,  that  is,  the  weight  of  the  mercury  sup- 
ported by  the  pressure  of  the  piston  will  be  measured  by  the 
whole  pressure  of  the  piston,  not  by  its  pressure  on  a  sur- 
face of  mercury  in  the  cylinder,  equal  merely  to  the  area  of 
the  tube  in  which  the  mercury  is  supported.  So  if  the  rise 
and  fall  of  the  mercury  in  the  barometer  are  proportional  to 
the  weight  of  the  air,  they  are  so  to  the  weight  of  all  the  air 
over  the  cistern  ;  but,  as  it  makes  no  difference  in  the  ac- 
tion of  the  barometer  whether  the  surface  of  the  cistern  is  of 
two  inches  area,  bearing  a  column  of  air  of  two  inches  area, 
or  is  an  ocean  of  mercury,  bearing  the  atmosphere  of  a  hemi- 
sphere, we  are  compelled  to  look  for  some  reason  besides 
the  weight  of  the  air  to  account  for  the  fact,  that  the  two 
surfaces  of  fluid  in  the  barometer  preserve  a  fixed  distance 
between  them.  In  other  words,  the  variation  in  the  length 
of  the  column  of  mercury  is  not  determined  by  a  correspond- 
ing variation  in  the  density  of  the  air. 

In  the  use  of  mercury  to  indicate  the  pressure  of  steam, 
or  of  the  condensed  air  of  blowing  cylinders,  the  extent  of  its 
rise  in  the  indicating  tube  corresponds  to  the  extent  of  the 
surface  of  mercury  exposed  to  it.  In  a  steam  gauge  the  area 
of  mercury  exposed  to  the  pressure  of  the  steam  bears  such 
a  proportion  to  the  area  of  mercury  in  the  indicating  tube, 
that  the  usual  range  of  force  is  measured  by  its  rise  and  fall. 


MECHANICAL  PHILOSOPHY.  127 

Now,  enlarge  the  surface  exposed  to  the  action  of  the  steam, 
give  it  an  area  equal  to  the  area  of  the  piston,  the  gauge 
would  burst  by  the  increased  pressure,  and  the  mercury  be 
thrown  with  violence  in  all  directions.  Take  out  the  baro- 
metrical tube  from  its  cistern,  and  place  it  in  an  ocean  of 
mercury,  its  range  would  not  change,  —  the  two  surfaces 
would  still  remain  at  the  same  distance  apart. 

Why  does  the  mercury  select  one  column  of  air  of  its  own 
area  and  answer  to  its  pressure,  regardless  of  the  pressure 
of  a  hundred  other  columns  of  the  same  size  and  weight 
which  bear  upon  the  cistern  ?  It  cannot  be  from  the  uni- 
form bore  of  the  tube  ;  for  the  tube  may  be  unequal,  either 
contracted  or  enlarged  ;  it  may  be  a  cone  with  its  base 
downward,  or  a  cone  with  its  base  upward ;  the  aperture 
or  opening  between  the  tube  and  cistern  may  be  larger  or 
smaller  than  the  bore  of  the  tube  ;  the  relative  quantity  of 
the  mercury  in  the  cistern  may  be  such,  that  on  bringing 
the  instrument  to  a  lower  level  it  will  nearly  all  be  drawn 
into  the  tube,  and  yet  will  remain  suspended,  so  that  in  this 
case,  if  the  mercury  is  sustained  at  all  by  the  atmosphere, 
it  is  by  a  column  of  less  area  than  the  bore  of  the  tube 
pressing  on  the  small  orifice  between  the  tube  and  cistern. 
There  is  indeed  nothing  in  the  action  of  the  barometer  which 
proves  that  the  mercury  in  the  tube  is  sustained  by  a  column 
of  air  of  its  own  area. 

Further  ;  if  it  were  possible  that  the  sustained  mercury 
under  any  circumstances  could  select  a  column  of  air  of  its 
own  area,  out  of  a  volume  of  air  pressing  by  elasticity  in  every 
direction,  and  disregard  the  pressure,  weight  and  elasticity  of 
other  columns  which  act  on  the  surface  of  the  cistern,  yet 
it  would  be  impossible  as  the  barometer  is  usually  con- 
structed. The  cistern  is  closed  at  top  ;  its  bottom  is  a  piece 


128  OUTLINES    OF   A   SYSTEM    OF 

of  leather  ;  the  instrument  is  inclosed  in  a  wooden  case  and 
suspended  perhaps  in  a  close  room.  It  then  receives  the 
pressure  or  weight  of  its  selected  column  of  air  forty-five 
miles  high,  one  quarter  of  an  inch  in  diameter,  which  may 
be  twisted  and  beat  about  by  the  winds  of  heaven,  and 
reaches  the  instrument  through  doors  or  windows,  passing 
through  the  air  in  the  room,  which  is  subject  to  expansion  and 
condensation  by  artificial  changes  of  heat.  Yet,  not  affected 
by  these  changes,  it  penetrates  through  the  openings  of  the 
wooden  case,  acts  on  the  bottom  of  the  leathern  support,  and 
still  gives  exactly  the  degree  of  pressure  belonging  to  its 
area,  to  the  mercury  in  the  tube  through  an  aperture  of 
any  size !  Is  it  possible  that  any  thing  can  be  measured 
by  such  an  instrument,  except,  perhaps,  the  elasticity  of  the 
air  in  the  apartment  in  which  it  stands,  which  would  affect 
the  whole  extent  of  the  surface  of  the  mercury  on  which  it 
acts? 

But  if  this  last  and  only  possible  action  of  the  air  by  its 
elasticity  be  the  cause  of  the  oscillation,  why  is  it  that  two 
upper  surfaces  of  mercury,  one  in  the  cistern  and  one  in 
the  tube,  are  an  essential  condition  of  the  oscillation  ?  A 
tube  in  a  conoidal  form  with  a  piece  of  leather  over  its  base, 
would  as  well  indicate  the  pressure  of  the  atmosphere.  The 
leather  would  act  as  well  thus  placed.  It  would  have  the 
same  elasticity.  The  air  pressing  on  it  would  act  as  truly 
without  an  upper  surface  of  mercury  as  with  it.  The  fact 
that  two  upper  surfaces  of  the  fluid  are  necessary,  abun- 
dantly proves  that  another  cause  for  the  action  of  the 
barometer  is  yet  to  be  discovered. 

In  our  examination  of  the  action  of  the  pump  and  of  the 
syphon,  we  hope  to  throw  more  light  on  the  subject  of  the 
elevation  and  support  of  fluids  by  means  of  a  vacuum. 


MECHANICAL    PHILOSOPHY.  129 

Surely  enough  has  been  already  said  to  throw  a  strong  sus- 
picion over  the  theory  which  explains  barometric  action  by 
atmospheric  pressure.  Indeed,  the  explanation  has  often 
been  received  with  some  distrust.  A  friend,  whose  strength 
of  mind  was  never  questioned,  said,  "  I  have  believed  the 
explanation,  relying  on  the  authority  which  gives  it,  rather 
than  because  it  satisfies  my  mind  ;  there  is  something  about 
the  action  of  the  barometer  which  is  not  yet  understood." 

If  both  the  construction  of  the  barometer  and  the  quali- 
ties of  the  atmosphere  are  such  as  to  throw  great  doubts 
over  the  supposed  action  of  the  weight  of  the  air  on  the 
mercury,  how  much  are  these  doubts  increased  when  it  is 
known  that  the  mercury  changes  its  level  in  the  tube,  under 
circumstances  which  forbid  the  idea  that  there  have  been 
equivalent  changes  in  the  density  of  the  air  ?  To  place  this 
matter  in  a  strong  light,  we  will  give  the  following  state- 
ment from  Humboldt's  Cosmos  :  —  "  The  horary  oscilla- 
tions of  the  barometer  between  the  tropics  present  two 
maxima,  namely,  at  9  or  9£  A.  M.,  and  10J  or  lOf  P.  M. ; 
and  two  minima,  at  4  or  4|,  P.  M.,  and  4  A.  M.,  occurring, 
therefore,  in  almost  the  hottest  and  coldest  hours.  Their 
regularity  is  so  great  that,  in  the  daytime  especially,  the 
hour  may  be  ascertained  from  the  height  of  the  mercurial 
column  without  an  error,  on  the  average,  of  more  than  fif- 
teen or  seventeen  minutes.  In  the  torrid  zones  of  the  New 
Continent,  on  the  coasts,  as  well  as  at  elevations  of  nearly 
thirteen  thousand  feet  above  the  level  of  the  sea,  where  the 
mean  temperature  falls  to  44°  6',  I  have  found  the  regular- 
ity of  the  ebb  and  flow  of  the  aerial  ocean  undisturbed  by 
storms,  hurricanes,  rain,  and  earthquakes." 

Can  we  receive  the  idea  conveyed  in  the  latter  clause  of 
this  quotation  ?  If  there  is  an  ebb  and  flow  of  the  aerial 


130  OUTLINES   OF  A   SYSTEM   OP 

ocean,  is  it  possible  that  its  regularity  should  remain  undis- 
turbed by  storms  and  hurricanes  ? 

If  the  oscillations  of  the  barometer  day  after  day,  month 
after  month,  are  as  regular  and  uniform  as  the  beating  of 
the  pendulum  of  the  clock,  these  changes  come  not  from  the 
capricious,  fitful  alterations  of  the  state  of  the  air.  The 
action  of  the  most  unrestrained  element  in  nature  gives  not 
results  the  most  exact  and  most  regularly  continued.  If, 
as  Humboldt  expressly  states,  the  horary  oscillations  of  the 
barometer  are  not  affected  by  changes  of  atmospheric  tem- 
perature, neither  by  heat  nor  by  cold,  by  snow  nor  by  rain, 
by  storm  nor  by  calm,  by  the  peace  of  nature  nor  by  the 
throe  of  the  elements,  if  the  changes  go  on  regularly  and 
periodically  on  the  plains  and  on  the  tops  of  high  mountains, 
surely  it  is  vain  to  seek  in  the  variations  of  atmospheric 
pressure  the  cause  of  these  oscillations. 

Geologists  have  often  noticed  that  the  changes  of  the 
level  of  different  portions  of  the  earth  are  complementary. 
There  is  a  rise  in  one  place  corresponding  to  the  fall  in 
another  place  ;  for  instance,  an  elevation  taking  place  in 
Sweden  is  responded  to  by  a  depression  in  Iceland.  Be 
Beaumont  calls  this  the  "  mouvement  de  bascule."  Besides 
these  occasional  movements  resulting  in  permanent  change, 
we  believe  that  there  are  periodical  fluctuations  of  the  surface 
of  the  earth  of  this  compensatory  nature,  occasioned  by  the 
varying  distribution  of  the  force  by  which  she  moves  in  her 
orbit.  This  fluctuation  would  enlarge  the  earth  in  one 
diameter,  and  contract  the  diameter  at  right  angles  with  this. 
Thus  there  are  two  daily  elevations  and  depressions  corres- 
ponding with  each  other.  This  gives  the  two  maxima  and 
minima  of  the  barometer. 

The  elliptical  form  of  the  earth's  circumference  is  depend- 


MECHANICAL    PHILOSOPHY.  131 

ent  on  her  position  as  being  nearer  to,  or  further  from  the 
centre  of  revolution ;  and  the  shrinking  or  expansion  is  regu. 
larly  propagated  by  her  rotation.  The  movement  being 
oscillatory,  the  maxima  will,  of  course,  be  somewhat  after 
noon  and  midnight,  corresponding  with  the  minima  of  the 
barometer.  The  extreme  would  also  be  greatest  within  the 
tropics.  Connected  with  this  subject  are  the  horary  changes 
of  the  horizontal  magnetic  intensity,  to  which  we  shall  here- 
after allude. 

To  one  other  fact  only  will  we  at  this  time  advert.  It  is 
stated,  on  good  authority,  that  the  barometer  is  more  to  be 
depended  on  for  determining  heights,  than  trigonometrical 
observations  are.  The  reason  given  is,  that "  the  refraction  of 
the  air  prevents  accurate  measurements  of  the  angle."  If 
we  are  correct,  the  reason  is  obvious  ;  but  it  is  impossible  that 
the  density  of  the  atmosphere  should,  under  all  disturbing 
influences,  always  correspond  to  elevation  with  a  greater 
accuracy  than  the  results  of  geometric  calculation. 

In  our  attempt  to  explain  the  cause  of  the  action  of  the 
barometer,  we  can,  in  this  place,  but  imperfectly  advance  the 
views  that  have  presented  themselves.  These  views  involve 
peculiar  ideas,  not  only  in  regard  to  the  force  of  rotation 
and  revolution,  but  to  the  vacuum,  to  the  action  of  fluids  in 
relation  to  their  own  particles,  and  to  their  action  in  relation 
to  other  matter ;  and  the  ideas,  to  be  presented  with  any 
distinctness,  must  be  gradually  unfolded  as  we  proceed. 

The  changes  of  the  mercury  result  in  a  longer  or  shorter 
column  of  the  fluid  in  rotation  as  one  mass.  In  the  rotation 
of  any  one  mass,  the  force  of  rotation  is  unequally  diffused 
through  it ;  the  parts,  say  the  upper  and  the  lower,  rotate 
with  greater  and  less  force.  This  inequality  of  present 
force  increases  with  the  distance  of  the  two  surfaces.  It 


132  OUTLINES    OF   A   SYSTEM    OF 

increases  also  with  the  density  of  the  mass,  the  distance  be- 
tween the  surfaces  remaining  the  same  ;  it  increases  by  a 
greater  degree  of  rotative  velocity,  in  a  mass  of  the  same 
density  and  same  distance  of  the  two  surfaces.  In  other 
words,  while  the  ratio  of  difference  remains  the  same  between 
the  different  parts  of  the  same  body,  the  actual  inequality  is 
increased  by  increased  extension,  or  density,  or  velocity. 

"We  have,  then,  an  unequally  distributed  rotative  force 
present  in  every  mass,  and  the  extent  of  the  inequality  is  in 
direct  proportion  to  the  difference  of  the  orbit  of  the  upper 
and  lower  extremities,  to  the  density  of  the  body,  and  to  the 
velocity  of  its  rotation. 

In  solids  bound  together  by  cohesion,  in  fluids  so  placed 
that  the  upper  and  lower  surfaces  cannot  approach  or  draw 
apart,  this  inequality  must  and  will  continue,  whatever  be 
their  depth,  density,  or  velocity  of  rotation.  But  from  the 
law  of  the  diffusion  of  force,  there  is  a  normal  difference  of 
diffusion  to  which  all  fluid  bodies  conform  when  free  to 
adjust  their  volume  in  relation  to  it. 

From  this  principle  comes  what  we  term  the  limit  of  ex- 
tension of  fluids,  —  a  distance  between  the  upper  and  lower 
surfaces,  which  measures  the  normal  inequality  of  the  pre- 
sent force,  —  an  idea  which  we  hope  fully  to  illustrate  as  we 
proceed.  At  present  we  merely  state  the  fact.  The  limit 
is  perceived  only  in  fluids  so  placed  that  a  change  can  be 
made  in  the  length  of  the  column.  This  is  the  case  with 
the  mercury  in  the  barometer.  It  can  shorten  or  lengthen 
its  column,  and  it  must  have  the  upper  and  lower  surfaces 
to  effect  this.  It  keeps  the  normal  inequality  the  same 
under  any  force  of  rotation,  by  extending  or  lessening  the 
distance  between  the  two  surfaces.  It  rotates  with  a  column 
which  corresponds  in  length  to  the  force  of  rotation.  If  the 


MECHANICAL  PHILOSOPHY.  133 

barometer  is  made  with  a  fluid  of  less  density  than  mercury, 
there  is  the  "  limit "  for  the  same  cause,  but  it  admits  of  a 
greater  distance  between  the  two  surfaces,  under  the  same 
force  of  rotation. 

We  dismiss  the  special  consideration  of  the  barometer,  with 
a  most  unhesitating  belief  that  its  action  is  caused  by  the 
increase  or  diminution  of  the  force  of  rotation, —  that  in  its 
changes  it  denotes  its  level,  —  that  it  indicates  directly  the 
altitude.  We  believe  so  from  the  fact  that  such  would  be 
its  action  as  deduced  from  principles  established  in  our  mind 
on  other  grounds.  We  also  believe  so,  because  we  find 
the  oscillations  always  to  be  such  as  could  be  occasioned  by 
changes  of  level,  and  often  such  as  could  never  be  produced 
by  varying  densities  of  the  atmosphere ;  and  because,  if  the 
atmosphere  be  of  varying  density,  the  construction  of  the 
barometer  is  such  that  it  could  not  be  affected  by  the  varia- 
tion. We  solicit  a  thorough  examination  of  this  subject ; 
for,  if  we  are  correct,  it  gives  a  value  to  the  instrument  far 
greater  than  it  now  possesses,  its  readings  being  at  present 
confined  to  atmospheric  pressure. 

We  pass  from  the  barometer,  hoping  further  to  elucidate 
its  action  by  examining  the  limit  of  extension  in  relation 
to  water.  The  principle  is  the  same  in  every  fluid  ;  but 
water,  for  many  obvious  reasons,  most  distinctly  illustrates 
the  opinions  that  we  would  present. 

Water,  in  a  tube  closed  at  the  top  and  open  at  the  bot- 
tom, on  being  immersed  in  water  will  remain  suspended  at 
any  height  within  the  limit.  But  if  the  top  of  the  tube  be 
opened  and  air  be  allowed  to  enter  it,  the  inclosed  water 
will  sink  to  the  level  of  the  water  in  which  the  tube  is  im- 
mersed. The  exclusion  of  air  from  the  tube  is,  therefore, 
12 


134  OUTLINES   OF  A   SYSTEM   OF 

the  condition  requisite  for  the  water  in  it  to  remain  above 
the  level  of  the  water  in  which  it  stands.  This  appears  of 
easy  explanation.  When  a  volume  of  water  is  in  contact 
with  air,  the  surface  of  this  volume  of  water,  if  at  rest,  will 
be  of  uniform  level.  In  the  two  elements,  air  and  water, 
there  is  a  difference  of  capacity  for  force,  so  that  the  one, 
when  in  contact  with  the  other,  invariably  retains  a  fixed 
degree  of  force  relative  to  the  other.  This  principle  gives 
uniformity  of  level  to  the  surface  ef  any  volume  of  water  in 
contact  with  air ;  but,  if  any  part  of  its  upper  surface  is  with- 
out this  contact,  its  level  of  rotation  does  not  depend  on  that 
which  gives  level  to  the  parts  of  the  surface  of  the  water 
which  are  in  contact  with  the  air. 

Under  the  theory  of  gravitation  it  is  supposed  that  it  is 
the  weight-  of  the  atmosphere  on  the  water  outside  of  the 
tube,  and  its  absence  within  it,  which  create  the  inequality 
of  pressure,  resulting  in  the  elevation  and  support  of  the 
water  in  the  tube.  This  is  supposed  to  be  shown  by  the 
action  of  the  atmospheric  pump,  by  the  syphon,  and  in  fact 
by  all  the  cases  of  the  elevation  of  wrater  which  exhibit  the 
law  of  extension.  It  is  considered  as  occasioned  by  the 
vacuum,  fluids  being  suspended  because  of  a  vacuum,  or 
because  there  would  be  a  vacuum  if  the  fluid  did  not  ascend. 

The  idea  is  not  distinctly  advanced  at  the  present  day  that 
the  action  of  the  fluid  is  from  an  attractive  power  of  the  va- 
cuum ;  but  the  inference  necessarily  drawn  from  the  facts  in 
connection  with  present  theories  is,  that  nature  so  abhors  a 
vacuum  that  action  is  immediately  induced,  not  only  to  fill 
the  vacuum  formed,  but  to  prevent  it  from  being  formed. 
There  is  always  a  supposition  of  aid  from  the  weight  of  an 
outside  column  of  air,  of  the  same  area  as  the  column  of 
heavier  fluid  to  be  acted  upon ;  but  in  no  case  can  the  action 


MECHANICAL    PHILOSOPHY.  135 

of  this  external  counterpoise  be  proved,  and  in  many  cases  it 
is  certain  that  it  does  not  exist  or  act.  In  a  succeeding 
chapter,  when  speaking  of  the  properties  of  air,  we  shall 
endeavor  to  illustrate  the  principle,  by  which  a  vacuum  arti- 
ficially created,  as  it  were,  draws  in  matter  to  fill  the  void 
space.  In  our  present  view  of  the  subject,  we  confine  our- 
selves to  the  illustration  of  the  idea,  that  the  support  of  a 
column  of  fluid  within  the  limit  of  extension  does  not  and 
cannot  depend  on  the  pressure  of  a  column  of  air  of  its  own 
area. 

We  will  suppose  a  common  atmospheric  pump,  working 
with  perfect  nicety,  and  with  the  least  possible  friction. 
The  piston  is  in  contact  with  the  surface  of  the  water  to  be 
raised,  and  on  being  lifted  the  water  is  raised  with  it.  There 
is  no  vacuum  here  ;  the  atmosphere  rests  on  the  piston,  and 
the  piston  on  the  water,  and  this  mutual  relation  of  atmo- 
sphere, piston,  and  water  continues.  The  piston  and  the 
water  below  it  are  not  in  the  least  relieved  of  the  weight  of 
the  aerial  column  over  them  ;  if  it  pressed  on  the  piston  be- 
fore it  was  moved,  it  equally  presses  when  it  is  moving 
upward.  If  the  pressure  of  an  equal  column  of  air  on  the 
water  of  the  cistern  raises  the  water  in  the  pump,  its  action 
prevents  a  vacuum  from  being  formed.  We  make  for  the 
present  the  simple  statement,  that  force  applied  to  the  water 
gives  it  power  to  rise  to  a  higher  level,  and  the  elevation  of 
the  piston  gives  it  space,  room,  freedom  to  ascend, —  the 
needed  force  for  ascent  is  supplied,  and  a  channel  opened 
for  the  action  of  the  force.  In  all  similar  cases  we  shall 
ever  find,  that  when  fluids  rise  in  pipes,  it  is  because  of  the 
application  of  force,  with  space  for  the  action  of  the  force. 

That,  in  the  case  of  the  pump  to  which  we  have  just 
alluded,  a  column  of  air  of  the  area  of  the  ascending  column 


136  OULTINES    OF   A   SYSTEM   OF 

of  water,  in  other  words,  atmospheric  pressure  on  the  water 
in  the  cistern,  does  not  lift  up  the  water  in  the  pump,  can 
be  most  distinctly  proved.  We  will  suppose  the  piston, 
which  touches  the  surface  of  the  water,  and  the  elevation  of 
which  gives  space  for  the  rise  of  the  water,  to  be  securely 
fastened  to  the  tube,  and  that  the  pump,  tube,  and  piston 
together,  be  lifted  as  high  as  the  piston  was  previously  lifted 
in  the  pump.  The  same  quantity  of  water  will  be  raised  as 
before.  In  the  one  case,  space  has  been  given  for  the  water 
to  rise  by  elevating  the  piston  ;  in  the  other,  by  elevating 
the  tube  with  the  stationary  piston.  The  force  required  to 
raise  the  tube,  valve  and  water  is  just  the  weight  of  the  tube, 
valve  and  water.  In  either  case  there  needs  to  be  supplied 
the  same  degree  of  force,  which  would  be  required  to  raise 
a  stone  of  the  same  weight.  How  then  can  it  be  said,  that 
in  working  the  pump,  the  pressure  of  the  atmosphere  is  the 
elevating  power,  when  for  every  pound  of  water  raised  the 
force  necessary  to  raise  a  pound  is  required  ? 

It  is  said  in  Ewbank's  Hydraulics  that  the  pump  will 
work  "  if  the  well  be  covered  with  slabs  of  stone,  and 
coated  all  over  with  the  best  hydraulic  cement,"  thus  cut- 
ting off  from  the  water  of  the  well  all  pressure  of  the  atmo- 
sphere, except  such  as  is  drawn  by  the  action  of  the  piston 
"  through  the  minute  pores."  The  only  necessary  con- 
nection with  the  atmosphere  is  limited  to  that  orifice,  which 
will  admit  into  the  well  a  volume  of  air  equal  to  the  volume 
of  water  withdrawn,  otherwise  there  would  certainly  be  a 
vacuum  formed  in  the  well.  No  connection  whatever  be- 
tween the  atmosphere  and  well  is  needed,  if  the  water  ele- 
vated runs  back  through  another  pipe  into  the  well.  The 
act  of  pumping  is  the  establishment  of  a  current  of  water. 
It  has  no  connection  whatever  with  atmospheric  pressure. 


MECHANICAL  PHILOSOPHY.  137 

A  pump  would  work  completely  immersed  under  water, 
there  establishing  a  connected  current,  and  after  the  cur- 
rent was  formed  the  upper  surface  of  the  water  would  not 
be  even  ruffled,  the  atmosphere  pressing  equally  on  all  the 
parts  of  the  current  below. 

It  is  said  that  the  atmosphere  presses  on  the  body  of 
every  man  with  a  force  of  some  fifteen  tons,  but  because  it 
bears  equally  in  every  direction,  because  it  is  so  exactly 
equipoised,  it  is  not  an  object  of  sensation.  We  do  not 
feel  it.  Its  force  is  neutralized,  destroyed,  so  far  at  least 
that  it  induces  no  perceptible  results.  This  is  true,  not 
only  in  relation  to  the  human  body,  but  to  every  mass  of 
matter  immersed  in  air.  The  cistern  and  the  water  that  it 
contains,  the  valves,  the  water  in  the  tube,  and  the  jet  of 
water  issuing  from  the  tube,  are  as  one  body ;  the  enfolding 
atmosphere  is  wrapped  around  the  whole  with  equal  strain. 
If  the  pressure  of  the  air  has  power  to  cause  the  water  to 
ascend  through  the  tube,  it  has  the  same  power  to  act  in 
the  opposite  direction.  If  it  press  water  in  at  the  bottom 
of  the  tube,  why  does  it  not  press  it  back  with  equal  force  ? 
When  the  upward  current  is  established  in  the  pump,  all  the 
force  to  create  the  current  must  be  supplied ;  the  force 
needed  is  exactly  equivalent  to  the  weight  of  water  elevated. 
Therefore,  the  doctrine  of  equal  areas  of  atmosphere  sup- 
porting the  denser  fluid  in  vacuo  has  no  more  application  to 
the  raising  of  water  by  the  pump,  than  it  has  to  the  drawing 
of  water  from  a  well  by  the  pole  and  bucket.  By  both 
mechanical  means  strength  is  put  forth  proportional  to  the 
quantity  of  water  to  be  raised,  and  to  the  distance  of  eleva- 
tion, the  weight  of  the  atmosphere,  so  far  as  any  practical 
result  is  concerned,  being  neutralized,  destroyed,  by  the 
affirmed  law  of  its  equal  pressure  in  every  direction. 

12* 


138 


OUTLINES    OF   A    SYSTEM   OF 


But  for  the  skeptical  we  will  mention  a  fact  which  per- 
fectly demonstrates  that  the  action  of  the  pump  has  no 
reference  to  the  pressure  of  the  atmosphere.  By  accident, 
in  Seville,  in  1766,  it  was  discovered  that  water  could  be 
raised  by  the  pump  fifty  feet  and  more,  if  a  small  opening 
was  made  for  the  admission  of  air  into  the  tube  of  the  pump. 
This  circumstance  excited  great  attention  at  the  time,  and 
was  supposed  to  prove  that  water  could  be  raised  by  atmo- 
spheric pressure  much  higher  than  thirty-three  feet. 

In  the  Journal  of  the  Franklin  Institute  for  May,  1837, 
it  is  stated  with  reference  to  the  action  of  pumps  worked  by 
steam,  that  a  little  air  is  sometimes  admitted  into  the  pump 
pipes,  which  "  makes  the  pump  work  more  lively  in  conse- 
quence of  the  spring  it  gives  to  the  column  of  water."  And 
in  the  same  paper,  Mr.  Perkins  states,  that  "  forty  years 
before  an  attempt  was  made  to  impose  upon  him  a  pump 
which  raised  water  by  atmospheric  pressure  one  hundred 
feet ;  but  he  detected  a  small  pin  hole  in  the  pipe  through 
which  the  air  was  admitted." 

These  facts  are  fatal  to  the  theory  that  atmospheric  press- 
ure causes  the  elevation  of  water  in  pumps ;  for  there  may 
be  the  pressure  on  the  ascending  as  well  as  on  the  impelling 
column.  No  matter  how  little  this  pressure  is,  though  the 
fact  was  shown  in  Ewbank's  well,  closed  by  hydraulic  cement, 
that  the  pressure  through  small  apertures  is  as  strong  as 
through  large, —  if  the  pressure  within  was  but  an  hundredth 
part  of  that  without,  what  there  was  of  it  would  balance  pro- 
portionally the  external  pressure,  and  to  this  extent  too  it 
would  impair  the  vacuum  ;  but  instead  of  this  it  gives  new 
power  of  ascent  to  the  water,  more  than  doubling  the  possi- 
ble extent  of  its  elevation.  To  account  for  this  we  are  told, 
"  It  was  ascertained,  on  investigation  of  these  facts,  that  the 


MECHANICAL  PHILOSOPHY.  139 

air  on  entering  the  pipe  mixed  with  the  water,  which  there- 
fore, instead  of  being  carried  up  in  an  unbroken  column, 
was  raised  in  disjointed  portions  or  in  the  form  of  thick  rain. 
This  mixture  being  much  lighter  than  water  could  be  sup- 
ported by  the  atmosphere,  and  by  proportioning  the  quantity 
of  air  to  be  admitted,  a  column  of  the  compound  fluid  may 
be  elevated  one  or  two  hundred  feet  by  the  atmosphere." 
In  this  explanation  the  fact  seems  to  be  forgotten,  that  it  is 
not  the  weight  of  the  column  of  water  which  determines  the 
altitude  to  which  it  can  be  raised.  Increase  the  force,  and 
ten  thousand  pounds  may  be  lifted  as  readily  as  ten  pounds. 
It  is  the  height  of  water,  not  the  weight,  which  attained,  it 
will  no  longer  rise  ;  and  the  main  fact  was  quite  forgotten, 
that  atmospheric  pressure  was  at  work  as  well  within  as 
without  the  tube. 

Our  views  can  be  presented  more  distinctly  by  reference 
to  the  action  of  the  syphon.  In  the  pump  the  current  is 
established  by  animal  force,  or  by  the  power  of  wind,  steam, 
&c.  applied  to  the  piston ;  in  the  syphon  the  same  end  is 
obtained  by  the  presence  of  a  longer  column  of  water  in  one 
leg  than  in  the  other.  To  use  the  common  language,  gravi- 
tation acting  on  the  longer  column  with  greater  force  than 
on  the  shorter,  the  equipoise  is  destroyed,  and  the  water 
falls  in  the  one,  rises  in  the  other,  thus  establishing  a  con- 
tinuous flow.  It  is  the  force  of  descent  of  one  body  drawing 
up  another  body  with  which  it  is  connected,  as  by  a  rope 
passing  over  a  wheel.  The  strength  of  the  flow  is  therefore 
determined  by  the  difference  in  height  of  the  two  columns, 
the  force  gained  by  the  descent  of  one  being  more  than 
sufficient  for  the  elevation  of  the  other.  The  flow  has  no 
reference  to  the  attraction  of  gravitation ;  for  by  different 
diameters  of  the  two  columns,  the  quantity  or  weight  of 
water  may  be  greatest  in  the  shorter  leg. 


140  OUTLINES    OF   A   SYSTEM   OF 

We  will  suppose  a  syphon,  the  shorter  leg  of  which  shall 
be  ten  feet  high,  containing  a  hundred  pounds  of  water,  its 
longer  leg  of  eleven  feet  containing  five  pounds  of  water. 
The  water  from  the  longer  leg  is  discharging  itself  into  the 
air  in  a  continuous  stream.  What  supports  the  one  hundred 
pounds  of  water,  which,  by  theory,  is  drawn  towards  the 
earth  by  a  force  equal  to  its  weight,  while  the  water  in  the 
longer  leg  is  drawn  down  by  a  force  of  only  five  pounds  ? 
Certainly  it  cannot  be  atmospheric  pressure  on  the  larger 
tube ;  for  there  is  also  atmospheric  pressure  at  the  discharging 
orifice  of  the  smaller  tube.  The  attraction  of  the  hundred 
pounds  of  water,  if  it  be  attracted  at  all,  should  be  suffi- 
cient to  draw  up  the  five  pounds  and  to  draw  in  the  air  after 
it.  Of  course  the  one  hundred  pounds  does  not  feel  the 
force  of  attraction. 

The  action  of  the  syphon  is  therefore  but  the  fall  of  water 
through  a  tube  arched  upward,  and  the  force  of  the  fall  is 
measured  by  the  difference  of  altitude  between  the  two 
levels,  —  that  from  which  it  is  drawn  and  that  into  which  it 
issues.  In  the  pump  it  appears  as  if  a  vacuum  were 
created,  as  if  the  current  were  established  by  the  weight 
of  the  air  pressing  on  the  water  in  the  well,  and  not  on  that 
in  the  tube.  In  the  syphon  there  is  not  the  most  remote 
indication  that  a  vacuum  is  formed,  and  the  pressure  of  the 
atmosphere  is  exactly  the  same  on  the  water  which  enters 
the  pipe,  and  on  that  which  leaves  it.  There  is  no  vacuum  ; 
for  the  syphon  is  kept  full  of  water,  and  this  creates  a  plenum 
as  much  as  if  it  were  filled  with  lead ;  and  with  the  shorter 
leg  immersed  in  water,  the  surface  of  which  is  at  a  higher 
level  than  that  in  which  the  longer  leg  is  immersed,  if  there 
be  any  difference,  the  atmosphere  presses  more  heavily  at  the 
discharging  than  at  the  receiving  orifice.  There  can  be  no 


MECHANICAL  PHILOSOPHY.  141 

pretence  of  atmospheric  action  on  a  current  of  water  flowing 
from  a  higher  to  a  lower  level,  through  a  tube  arched  up- 
wards. The  air  in  this  case  has  no  more  to  do  with  the 
current  than  if  it  flowed  through  a  pipe  bent  downward,  or 
curved  laterally,  —  no  more  than  if  the  water  ran  down 
through  a  straight  tube,  or  without  any  tube  through  an 
orifice  in  the  side  of  the  containing  vessel.  The  action  of 
the  syphon  is  imputed  to  atmospheric  pressure,  because  the 
limit  to  which  water  can  rise  in  it  is  the  limit,  beyond  which 
water  cannot  be  raised  in  the  cases  in  which  atmospheric 
pressure  is  supposed  to  be  the  cause  of  the  elevation.  It  is 
true  that  if  the  water  at  the  top  of  the  syphon  should  part, 
and  it  should  descend  in  each  column,  there  would  be  a 
vacuum  ;  but,  there  being  no  gravitation,  it  will  not  part  till 
beyond  the  limit  of  extension.  It  then  parts  through  the 
action  of  the  law  which  regulates  the  limit.  But  because,  if 
the  syphon  does  not  establish  its  current,  and  the  water  falls 
in  both  the  legs,  there  is  a  vacuum,  it  does  not  follow  that  a 
vacuum  or  the  dread  of  one  establishes  the  current  when  it 
flows.  While  the  current  is  flowing  there  is,  if  any,  an  equal 
pressure  at  both  ends,  and  from  them  up  through  the  whole 
length  of  the  pipe. 

The  vacuum  is  formed,  if  the  syphon  be  raised  above  the 
limit.  If  the  instrument  be  extended  higher,  the  water  does 
not  rise ;  but  remains  elevated  at  an  equal  height  in  both 
legs,  measuring  from  the  respective  levels  of  the  surfaces  of 
the  water  in  which  they  are  immersed.  It  is  supposed,  that 
each  suspended  column  is  counterpoised  by  an  equal  weight 
of  atmosphere,  that  is,  by  a  column  of  air  of  the  same  area 
as  the  suspended  column  of  water.  Of  course,  this  being 
the  case,  any  variation  of  the  limit  marks  an  equivalent 
change  in  atmospheric  weight. 


142  OUTLINES    OF   A   SYSTEM    OF 

Without  going  into  the  question  at  this  time,  of  the  pos- 
sible efficacy  of  the  air  in  sustaining  water  in  such  cases, 
which  may  well  be  doubted,  as  we  have  seen  that  it  has  not 
the  most  remote  agency  in  giving  it  its  elevation,  we  feel 
confident  that  the  weight  of  the  suspended  column  does  not 
weigh  a  column  of  air  of  its  own  area. 

If  water  be  subjected  to  pressure  in  a  cylinder  by  a  pis- 
ton acting  on  its  upper  surface,  the  rise  of  water  issuing  or 
sustained  by  the  pressure  is  measured  by  the  whole  amount 
of  the  force  of  the  piston,  as  in  the  case  of  a  forcing-pump. 
If  the  atmosphere  presses  on  the  surface  of  water  in  a  pond, 
or  in  a  small  vessel,  the  pressure  is  measurable  by  the  force 
acting  on  the  whole  surface.  A  pond  a  mile  in  area  bears 
the  pressure  of  a  column  of  air  a  mile  in  area  ;  and  the 
water  in  a  small  vessel  bears  the  pressure  of  the  column 
over  it.  On  this  principle  only  can  water  be  acted  on  by 
the  air,  and  any  variations  of  pressure  arising  from  atmo- 
spheric changes  would  express  the  variations  of  the  weight 
of  the  whole  volume  of  air  over  the  pressed  surface. 

Thus  far  we  have  considered  the  limit  of  extension  of 
fluids,  and  appear  to  find  that  this  limit  is  not  determined 
by  the  gravitation  of  the  fluid,  since  the  quantity  sustained 
under  the  same  circumstances  may  be  one  pound,  or  one 
thousand  pounds  ;  nor  by  the  gravitation  of  the  air  on  the 
exposed  surface  of  the  fluid,  since  this  may  be  one  inch  or  a 
thousand  miles  in  area  ;  nor  by  any  virtue  or  efficacy  of  the 
vacuum,  since  it  may  be  equally  filled,  saturated,  and  thus 
destroyed  by  matter  of  its  own  volume,  whether  the  matter 
drawn  to  fill  it  is  light  as  air  or  dense  as  mercury.  The 
limit  is  therefore  not  caused  or  determined  by  the  gravitat- 
ing power. 

We  advance  to  a  farther  consideration,  •—  to  create  the 


MECHANICAL  PHILOSOPHY.  143 

limit,  it  is  not  necessary  that  the  fluid  be  confined  in  pipes 
or  vessels.  Water  out  of  pipes,  unconfined,  in  the  free  air, 
obeys  the  law.  The  waters  of  the  ocean  respond  to  this 
limit.  Water-spouts,  with  mingled  air,  may  raise  a  broken 
column  to  a  higher  range  ;  the  waves  may  dash  themselves 
farther  up  on  a  rocky  coast.  Wave  may  be  formed  on 
wave,  a  new  limit  of  extension  may  perhaps  be  formed  upon 
the  original  limit,  an  ocean  wave  upon  a  tidal  wave  ;  but 
recorded  events  always  give  a  height  of  the  rise  of  floods, 
which  denotes  the  bound  assigned  by  nature  to  the  heaping 
up  of  the  waters. 

It  is  difficult  to  measure  the  height  of  a  wave,  and  impos- 
sible to  separate  exactly  the  unbroken  water  from  the  crest 
which  is  mingled  with  air.  We  know,  however,  that  the  rise 
of  waves  is  less  than  thirty-four  feet  in  the  most  violent 
storm.  One  measurement  taken  in  a  long-continued  heavy 
gale  gave  thirty-two  and  a  half  feet  from  elevation  to  de- 
pression ;  on  striking  a  wall  of  rock,  the  unbroken  column 
ascended  sixty-five  feet  from  the  level  of  the  ocean,  dashing 
its  spray  much  higher.  The  extent  of  the  rise  of  the  tide 
in  the  bays  of  Fundy  and  of  St.  Malo  is  said  to  be  sixty 
feet,  and  the  reference  to  heights  of  which  the  simple  limit 
forms  the  root  or  multiple,  in  the  statements  of  the  rise  of 
floods,  is  so  frequent  as  to  indicate  some  principle.  It  is 
certain,  however^that  the  waves  of  the  ocean  have  a  fixed 
limit  corresponding  to  the  limit  of  the  extension  of  water  in 
tubes. 

The  isolated  fact  of  the  limit  is  thus  advanced  to  an  uni- 
versal principle; 'for  it  has  never  been  imagined  that  an 
unequal  atmospheric  pressure  causes  the  rise  of  the  waves. 
Whenever  a  fluid  is  so  placed  that  its  degree  of  extension 
upwards  and  downwards  can  be  changed  or  modified,  when 


144  OUTLINES    OF   A    SYSTEM   OF 

it  is  free  to  assume  its  own  position,  it  obeys  the  law  of  limit. 
To  give  it  a  greater  extension  as  one  mass,  it  must  be  re- 
strained or  confined.  Its  spread  or  dilation  in  breadth  must 
be  prevented,  either  artificially  as  in  tubes,  or  naturally  as 
in  a  containing  basin.  Its  base  must  be  cut  off,  —  it  must 
be  separated  from  other  volumes  of  the  same  fluid.  Water 
can  be  elevated  to  any  height  by  the  lifting  pump,  or  by  the 
application  in  any  manner  of  force  beneath  the  volume  of 
water  to  be  raised.  But  if  the  force  be  applied  from  above, 
as  in  the  atmospheric  pump,  or  in  any  manner  to  a  body  of 
water  remaining  in  connection  with  other  water,  the  force 
applied  is  conveyed  away  from  the  special  volume  to  the 
whole  volume  ;  a  portion  therefore  cannot  be  elevated.  It 
must  first  be  separated,  that  the  force  applied  may  act  upon 
it.  It  will  then  rise ;  but  before  the  separation  the  force 
applied  is  communicated  to  the  whole  volume.  It  is  thus 
that  separated  volumes  may  be  lifted  to  any  height,  if  suffi- 
cient force  be  used  ;  and  this  explains  the  fact  before  alluded 
to,  that,  when  air  was  admitted  into  the  pump  by  a  perfora- 
tion in  the  tube,  water  was  lifted  beyond  the  limit,  since  the 
air  separated  the  one  volume  into  detached  portions. 

The  limit  of  extension  is  therefore  the  degree  to  which 
fluids  can  be  drawn  upward  in  an  unbroken  column.  It  is 
the  limit  of  the  inequality  in  the  distribution  of  the  force  of 
rotation,  which  will  remain  when  the  e^ess  can  be  trans- 
ferred to  another  portion  of  the  same  volume.  It  is  the 
limit  of  elasticity  of  form  ;  for  while  a  solid  body  ever  retains 
one  extension,  —  no  one  part  of  it  being  susceptible  of  ele- 
vation independently  of  the  other  parts  of  the  mass,  to  raise 
one  part  requiring  force  sufficient  to  raise  the  whole,  —  por- 
tions of  fluids  can  be  drawn  up,  force,  to  a  limited  degree, 
confining  itself  to  the  part.  Thus,  a  column  of  water  can 


MECHANICAL    PHILOSOPHY.  145 

be  extended  from  the  volume  ;  but  beyond  this  limit  force  no 
longer  confines  itself  to  the  part  to  which  it  is  applied,  but 
diffuses  itself  through  the  whole  volume.  Therefore,  the 
sea  knows  its  place ;  the  level  of  the  waters  composing 
so  large  a  relative  portion  of  the  globe  is  preserved,  not 
with  a  dead  uniformity,  not  with  a  rigid  flatness  of  sur- 
face, but  with  constant  changes,  limited  undulations  ;  and 
the  ocean,  free  to  move,  yet  under  the  law  of  extension,  is 
as  securely  bound,  as  are  the  rocky  cliffs  against  which  its 
rolling  surface  strikes. 

The  more  our  attention  is  directed  to  the  unfathomable 
deep,  the  more  wonderful  appears  the  action  of  the  laws 
which  control  it.  We  are  taught  to  regard  the  vaporization 
of  the  surface  of  the  ocean  as  a  means  by  which  the  equili- 
brium of  heat  is  preserved,  and  by  which  the  waters  circu- 
late from  the  sea  to  the  clouds,  from  the  clouds  to  the 
thirsty  earth,  and  again  collecting  in  swelling  streams  return 
back  to  the  ocean  in  a  never-ceasing  flow.  How  great  the 
quantity  of  fluid  thus  in  constant  change,  hundreds  of 
millions  of  tons  rising  in  one  day  from  the  comparatively 
small  extent  of  the  Mediterranean  Sea,  the  quantity  ever 
rising  from  the  entire  surface  of  the  waters  of  the  globe, 
from  the  frozen  polar  seas,  as  well  as  from  the  tepid  oceans 
of  the  torrid  zones,  being  beyond  all  estimate  ! 

This  vaporization  not  only  waters  the  earth,  not  only 
restores  the  equilibrium  of  temperature,  these  effects  being 
as  it  were  the  incidental  mercy  of  the  law  of  nature  ;  but 
it  is  the  preservation  of  an  equilibrium  si  force.  The  ocean 
exhausts  itself  of  the  strength  not  necessary  for  its  level  of 
motion,  the  vapor  draws  off  the  excess  of  energy,  and  the 
waters  preserve  their  equable  flow.  The  risen  vapor,  again 
condensing,  slowly  imparts  a  quickening  impulse  to  the  slug- 
is 


146  OUTLINES   OF  A   SYSTEM   OF 

gishly  moving  air,  or  rapidly  throws  out  the  force  in  the  light- 
ning's flash,  giving  to  some  portion  of  the  earth  the  needed 
impulse.  For  this  reason  is  there  greater  condensation, 
more  copious  rain,  in  high  lands  and  mountainous  regions, 
•which  from  their  elevation  require  the  added  force. 

No  one  can  contemplate  the  extent  of  the  oceans  of  the 
globe,  —  their  vast  surface  compared  with  the  land, — without 
being  assured  that  this  unequal  distribution  is  not  from  acci- 
dent, —  without  the  belief  that  there  is  connected  with  it  the 
furtherance  of  some  great  design.  And  when  we  consider 
its  relations  to  force,  its  strong  conducting  power,  we  see  a 
reason  for  the  ocean's  vastness,  and  comprehend  its  action  in 
the  economy  of  nature.  There  is  a  reason  too  for  the  pre- 
ponderance of  water  in  the  southern  over  the  northern 
hemisphere,  which  may  yet  be  discovered  by  man  ;  for, 
though  land  and  water  seem  confusedly  mingled  as  if  with- 
out law,  not  by  accident  came  the  position  of  the  smallest 
island,  nor  the  bounds  of  the  paltriest  lake. 

Then  again,  the  waters  of  the  ocean  have  a  molecular 
action,  increasing  in  intensity  as  they  deepen.  The  experi- 
ments of  Scoresby,  —  the  well-known  fact  of  the  breaking  of 
a  vessel  containing  air  when  let  down  to  a  certain  depth, — 
the  bursting  of  a  tight,  full  cask,  by  the  insertion  of  a  long 
slender  tube  filled  with  water, — the  "spring"  of  water,  of 
which  mechanics  take  advantage  in  their  management  of 
water-power,  by  narrowing  the  aperture  through  which  the 
water  flows,  —  the  eflect  of  conical  ajutages,  by  which  the 
flow  of  water  from  a  discharging  orifice  is  greatly  increased 
from  the  transfer  of  the  molecular  action  into  the  progressive 
motion  of  the  moving  jet,  —  all  these  facts  together  prove 
that  there  is  an  increase  of  the  atomic  action  of  water  pro- 
portional to  the  distance  from  the  surface,  and  that  this 


MECHANICAL  PHILOSOPHY.  147 

change  is  not  in  the  least  dependent  on  a  force  of  gravita- 
tion ;  for  water  is  almost  incompressible,  and,  were  it  com- 
pressed, the  increase  of  molecular  action  is  altogether  too 
rapid  for  the  rate  of  increase  of  gravitation,  according  to 
the  distance  from  the  centre. 

Thus  the  waters  receive  and  retain  a  greater  force  than 
is  needed  for  rotation,  resolving  it  into  molecular  action,  the 
ocean  becoming,  as  it  were,  the  storehouse  of  force,  from 
which  it  may  be  gradually  imparted  according  as  it  is 
needed  for  the  motions  of  the  various  parts  of  the  earth. 
It  is  by  this  provision  that  force  divides  or  diffuses  itself 
equally  throughout  the  volume  of  the  fluid ;  for,  as  stratum 
after  stratum  requires  the  less  for  rotation,  the  unused  force 
is  employed  in  molecular  motion.  It  is  by  this  equal  diffu- 
sion that  the  movable  element  preserves  its  continuity  ;  and, 
without  the  bonds  of  cohesion  to  hold  its  particles  together, 
it  moves  with  the  earth  as  one  mass,  no  portion  ever  raising 
itself  beyond  the  limit,  or  floating  in  the  atmosphere  in 
detached  masses.  Without  this  provision,  the  air  would  not 
be  divided  from  the  waters,  element  would  not  be  separated 
from  element,  the  waters  could  not  be  gathered  together  into 
one  place. 

It  appears  evident,  then,  that  there  is  in  water  and  other 
fluids  a  molecular  action,  which  increases  in  intensity  accord- 
ing to  the  depth,  or  distance  from  the  surface.  On  the  other 
hand,  the  rotative  force  increases  as  it  ascends  from  the 
depths,  being  greatest  at  the  surface.  One  therefore  is  the 
complement  of  the  other,  each  being  capable  of  resolution 
into  the  other.  Therefore,  force  is  ever  equally  diffused 
through  the  same  volume,  the  aggregate  of  force  being 
evenly  distributed  through  each  body  of  water,  whatever  its 
depth  or  extent.  It  is  therefore  equal  throughout  the  space 
occupied  by  the  water. 


148  OUTLINES    OF   A    SYSTEM   OF 

How  far  extends  this  principle  of  the  equal  distribution  of 
force  relative  to  space  ?  Is  it  universal,  in  solids  and  fluids, 
from  the  densest  matter  to  that  which  makes  the  nearest 
approach  to  a  vacuum  ?  Do  accelerated  and  retarded  motion 
take  place  from  the  adjustments  of  force,  as  in  different 
degrees  it  acts  in  the  atoms  and  in  the  mass,  in  the  mole- 
cular and  the  progressive  motion  ?  Is  it  a  normal  adjust- 
ment which  gives  harmony  of  movement  to  the  spheres  ? 
Is  motion  irrespective  of  mass  ?  Has  the  rarer  medium 
of  the  atmosphere,  for  instance,  an  increase  of  molecular 
action  to  compensate,  as  it  were,  for  its  less  quantity  of 
progressive  motion  in  a  given  space  ?  This  indeed  opens  a 
wide  range  of  thought ;  but  we  pause  in  the  inquiry.  May 
we  not  hope  that  in  time  to  come  the  intellect  of  man  may 
be  able  to  penetrate  these  mysteries,  and  to  find  in  the 
now  complicated  phenomena  of  motion  that  simplicity  and 
comprehensibility,  which  belong  to  every  domain  of  nature  ? 
If  force  be  equally  diffused  through  space,  and  we  extend 
the  idea  of  the  equality  of  its  diffusion  to  limitless  space, 
the  human  mind  almost  shrinks  back  at  the  contemplation 
of  this  expanse  of  energy.  There  is  but  one  step  farther 
which  it  can  take,  going  on  from  boundless  force  to  Him 
from  whom  it  is  the  emanation. 

To  return :  there  is  then  by  fixed  laws  a  permanence 
given  to  the  free-moving  elements.  There  is  a  defined  limit 
of  extension,  measured  by  the  density  of  the  fluid,  and  by 
the  velocity  of  its  motion.  This  is  determined  by  the  degree 
of  the  inequality  of  force  which  will  be  retained  by  any 
volume  of  fluid,  so  placed  that  it  can  transfer  the  added 
force.  Broken  columns  of  water  may  be  elevated  to  any 
range  of  rotation ;  but  water  resting  on  water  as  its  base, 
refuses  to  extend  itself,  or  to  be  drawn  out  above  its  normal 


MECHANICAL  PHILOSOPHY.  149 

range.  Beyond  this,  force  -will  not  so  adjust  itself  as  to 
keep  it  one  mass ;  if  you  apply  force,  the  water  receives 
it,  but  will  not  retain  it.  The  raging  storm  passing  over  the 
wide  ocean,  ever  imparting  force,  gives  to  the  water  a  defi- 
nite range  of  altitude  only,  while  the  excess  is  silently  trans- 
ferred to  the  deeps  below.  Urge  it  further  and  further,  it 
still  refuses  to  rise,  and,  if  saturated,  if  it  can  retain  no  more 
in  the  intensity  of  molecular  action,  the  water  at  the  surface 
changes  into  vapor  and  floats  upward  in  harmless  cloud- 
wreaths. 

"  And  God  said,  I  will  establish  my  covenant  with  you, 
neither  shall  all  flesh  be  cut  off  any  more  by  the  waters  of  a 
flood,  neither  shall  there  any  more  be  a  flood  to  destroy  the 
earth.  I  do  set  my  bow  in  the  clouds,  and  it  shall  be  for  a 
token  of  a  covenant  between  me  and  the  earth." 

The  bow  in  the  cloud  has  been  by  many  looked  upon  as 
a  figure  of  speech  only,  as  a  beautiful  metaphor,  possessing 
no  more  significance  than  the  clear  sunshine  after  the  falling 
rain.  It  has  not  been  connected  in  men's  minds  with  any 
law  of  nature,  which  determines  the  limit  of  the  rise  of  the 
waters.  Yet  it  is  the  expression  of  the  law  by  which  the 
floods  keep  their  place.  It  connects  science  with  the  writ- 
ten Word.  Understood,  the  rainbow  shows  the  harmony  of 
the  creation  with  the  voice  of  God.  It  practically  as  well 
as  spiritually  records  the  covenant. 

The  water  ascends  from  its  immense  ocean  bed  only  as 
the  vapor  of  the  clouds.  It  cannot  rise  to  deluge  the  earth. 
The  flowing  stands  firm,  the  free  moving  element  is  bound 
in  chains  ;  for  though  intense  force,  in  its  might,  may  rush 
across  the  rolling  waves,  it  will  not  impart  to  them  the  power 
to  rise  above  a  fixed  limit,  except  as  vapor,  and  on  the 

13* 


150 

clouds  the  covenant  is  written  in  the  vivid  colors  of  the  rays 
of  the  sun. 

Devoutly  thankful  should  we  be  when  reason  thus  re- 
echoes the  voice  of  God,  —  when  science,  in  her  feeble 
utterance,  repeats  the  declarations  of  Scripture. 

We  cannot,  with  the  thought  of  this  connection,  look  upon 
the  bow  in  the  clouds  but  with  increased  delight,  and  with  a 
strengthened  reverence  for  the  written  Word,  —  with  some- 
what of  the  feeling  which  prompted  the  exclamation  of  Cole- 
ridge, "  What  a  mine  of  undiscovered  treasures,  what  a  new 
world  of  power  and  truth,  does  the  Bible  promise  to  our  future 
meditation,  when  in  some  gracious  moment,  one  solitary  text 
of  all  its  inspired  contents  dawns  upon  us  in  the  pure  un- 
troubled brightness  of  an  idea,  which  even  as  the  light,  its 
material  symbol,  reflects  itself  from  a  thousand  surfaces! " 


CHAPTER  VII. 


"THERE  ARE  INDEED  MANY  THINGS  IN  THE  FRAME  OF  NATURE,  WHICH 
WE  CANNOT  REACH  TO  THE  REASONS  OF,  THEY  BEING  MADE  BY  A 
KNOWLEDGE  FAR  SUPERIOR  AND  TRANSCENDENT  TO  THAT  OF  OURS, 
AND  OUR  EXPERIENCE  AND  RATIOCINATION  BUT  SLOWLY  DISCOVER- 
ING THE  CONTRIVANCES  OF  PROVIDENCE  THEREIN. 

"NO  MAN  EVER  WAS  OR  CAN  BE  DECEIVED  IN  TAKING  THAT  FOR  A 
TRUTH  WHICH  HE  CLEARLY  AND  DISTINCTLY  APPREHENDS,  BUT  ONLY 
IN  ASSENTING  TO  THINGS  NOT  CLEARLY  APPREHENDED  BY  HIM."  — 
Cudworth. 

WE  continue  our  examination  of  the  action  of  force  upon 
fluids.  Our  views  bring  us  to  the  conclusion  that  there  is 
no  weight  or  pressure  of  the  particles  of  water  against  each 
other,  against  a  containing  vessel,  or  against  a  foreign  body 
immersed,  other  than  arises  from  the  force  of  molecular 
action,  which  manifests  itself  under  certain  circumstances. 
We  do  not  believe  that  gravitation  presses  together  the 
particles  of  water,  or  presses  them  against  an  immersed 
body. 

This  proposition  at  first  sight  appears  to  contradict  the 
generally  received  opinions  on  the  subject.  It  is  not  so. 
Though  expressed  in  different  language,  our  proposition  is  in 
harmony  with  established  views.  The  law  of  gravitation  is 
modified  in  its  application  to  fluids.  It  is  said,  u  the  par- 
ticles of  fluids  gravitate  independently  of  each  other,  not 
only  downwards,  but  upwards  and  sideways."  "  The  press- 
ure of  fluids  is  equal  in  all  directions,  being  founded  on  the 


152  OUTLINES   OF   A   SYSTEM   OF 

complete  intermobility  of  the  particles  of  the  fluid,  and  on 
the  equal  propagation  of  pressure  in  every  direction." 
"  When  a  fluid  is  at  rest  the  pressure  will  be  nothing,  be- 
cause the  opposite  dead  pressures  will  be  equal."  These 
quotations  are  from  the  highest  authority,  and  completely 
prove  the  proposition  with  which  this  chapter  commences, 
so  far  at  least  as  relates  to  any  result  from  the  pressure. 

Admitting,  however,  the  theory  that  the  atoms  of  water 
do  press  against  each  other,  and  against  an  immersed  body, 
the  pressure,  if  it  is  equal  in  every  direction,  cannot  proceed 
from  an  attraction  of  gravitation  drawing  towards  the  centre 
of  the  earth.  Why  this  equal  pressure,  of  the  existence  of 
which  there  can  be  no  proof,  is  attributed  to  a  force  acting 
downward  only,  does  not  appear. 

A  consideration  of  the  weight  of  a  mass  of  matter  rigidly 
at  one  level,  or  of  the  pressure  of  one  mass  against  another, 
or  of  the  mutual  pressure  of  their  atoms  when  relatively  at 
perfect  rest,  involves  what  may  be  called  transcendental 
dynamics.  It  treats  of  a  tendency  to  fall,  a  tendency  of 
the  particles  of  matter  to  move  against  each  other,  which 
is  followed  by  no  action.  The  tendency  to  fall,  of  a  body 
secured  so  rigidly  that  it  cannot  be  moved,  can  never  be  the 
subject  of  experiment.  We  can  measure  force  only  by 
resultant  motion.  There  is  no  force  of  descent  unless  there 
is  a  descent.  A  body  secured  at  one  level  at  perfect  rest, 
would  feel  heavy  only  by  the  upward  pressure  of  the  hand 
against  it.  Suppose  a  body  which  by  its  fall  presses  a  spiral 
spring,  the  weight  of  the  body  is  its  force  of  descent  upon  the 
spring,  which,  if  it  have  not  force  of  elasticity  enough  to 
throw  it  back,  will  remain  compressed.  The  compression  is 
a  change  in  the  position  and  arrangement  of  the  atoms  com- 
posing the  spring.  This  comparison  will  indicate  the  reason 


MECHANICAL  PHILOSOPHY.  153 

of  the  feeling  of  pressure  in  the  hand  supporting  any  mass 
of  matter. 

We  will  suppose  a  vessel  ten  feet  high  containing  water. 
From  an  aperture  near  the  upper  surface  the  water  will 
run  with  but  little  force,  falling  down  almost  perpendic- 
ularly ;  from  an  aperture  in  the  middle  it  spouts  with  con- 
siderable power ;  and  from  one  at  the  bottom  the  flow  is 
with  greatly  increased  energy.  The  jet  is  horizontal  in 
proportion  to  the  distance  of  the  orifice  from  the  upper  sur- 
face ;  its  force  is  in  proportion  to  the  descent  of  the  water 
inside  the  vessel.  There  is  little  or  no  force  of  descent  in 
the  water  flowing  from  the  upper  orifice,  —  the  whole  force  of 
descent  is  in  that  flowing  from  the  lower  opening.  It  is  the 
force  of  descent  which  impels  the  water,  not  abstract  weight 
or  tendency  to  descend ;  for  a  pound  of  water  at  the  surface 
has  as  much  desire  to  go  down,  is  as  much  attracted,  as  a 
pound  at  the  bottom  of  the  vessel,  that  is,  neither  is  at- 
tracted to  the  earth.  Matter  itself  is  inert,  without  power 
to  move  or  tendency  to  move.  It  obeys  the  law  of  force, 
and  if  absolutely  at  rest  it  is  without  force  ;  nothing  can  be 
affirmed  of  it,  but  that  it  is,  —  the  fact  that  it  exists  in 
space.  We  proceed  to  more  practical  illustrations  of  the 
pressure  and  equilibrium  of  fluids. 

We  will  describe  from  nature.  We  were  leaning  on  the 
rail  of  a  bridge,  a  few  rods  above  which  rose  a  dam  about 
ten  feet  in  height,  which  held  back  a  pond  of  water  extend- 
ing beyond  the  dam  for  at  least  a  mile.  The  dam  was  per- 
haps two  hundred  feet  long,  it  was  old  and  dilapidated, 
and  from  between  the  logs  there  were  at  every  height 
countless  jets  of  water.  On  the  top  of  the  dam  was  a  flash 
board.  —  a  plank  placed  edgewise,  slightly  secured,  to  in- 
crease the  height  of  the  dam.  At  one  place  this  flash  board 


154  OUTLINES   OF  A   SYSTEM   OF 

had  given  way,  and  there  the  water  poured  over  the  dam  in 
an  unbroken  sheet.  We  will  look  at  this  dam  with  its  many 
jets  of  water,  the  broad  sheet  tumbling  over  a  part  of  it,  to 
understand  the  nature  of  the  pressure  of  water.  It  will  give 
us  the  truth,  if  observed  with  minds  free'from  all  predeter- 
mined theories. 

In  the  first  place,  we  see  that  the  water  does  not  press 
equally  in  all  directions,  upward,  downward  and  sideways  ; 
for  the  lower  jets  of  water  issue  with  much  more  force 
than  the  upper  jets.  There  is  a  gradual  diminution  of 
pressure  from  the  lowest  to  the  highest ;  the  top  of  the 
water  falling  over  the  dam  does  not  press  at  all,  for  the  sur- 
face retreats,  forming  a  curve.  The  pressure  increases 
from  the  surface  to  the  bottom.  Fluids  do  not  gravitate 
equally  in  every  direction,  or  the  force  of  gravitation  would 
have  thrown  out  equal  jets  from  the  top  to  the  bottom. 
Perhaps  the  water  gravitates  downward  only.  That  cannot 
be  the  case ;  for  then  there  would  be  no  lateral  pressure, 
but  at  each  jet  the  water  would  flow  nearly  without  force. 
One  other  thing  is  certain,  that  this  great  volume  of  water, 
two  hundred  feet  broad  and  a  mile  long,  does  not  press 
laterally  with  a  weight  in  proportion  to  the  mass  of  the 
heaped  up  water.  So  weak  an  inclosure  could  hardly  bear 
a  ton's  weight.  There  is  lateral  force  then  only  in  that  water 
which  runs  over  the  dam,  or  escapes  through  the  apertures. 
That  which  is  at  rest  can  have  no  pressure ;  for,  if  it  had, 
the  weak  barrier  would  be  overthrown. 

Suppose  a  stone  weighing  one  hundred  pounds,  pressed 
equally  one  very  side  by  springs.  With  the  pressure  of 
these  springs  it  weighs  just  one  hundre.d  pounds  as  it  did 
without  them ;  for  the  action  of  one  spring  neutralizes  the 
pressure  of  the  opposite  spring,  so  that  the  "gravity"  of 


MECHANICAL  PHILOSOPHY".  155 

the  stone  is  not  changed.  We  will  take  away  the  springs 
and  weigh  this  stone  under  water,  which  by  theory  presses 
on  it  as  did  the  springs,  equally  in  every  direction.  It  has 
lost  weight,  —  therefore  water  does  not  press  equally  in  all 
directions  on  the  stone.  Nor  does  the  water  press  down- 
ward only  ;  for  in  this  case  the  stone  would  weigh  more  in 
water,  "  having  to  bear  not  only  its  own  share  of  attractive 
force,  but  the  weight  of  all  the  strata  (of  water)  over  it." 

How,  then,  can  we  ascertain  the  specific  gravity  of  the 
stone  on  both  or  either  of  the  two  laws  of  the  gravitation  of 
fluids  ?  An  equal  pressure  on  all  sides  would  be  "  dead 
pressure,"  and  the  stone  would  weigh  the  same  in  water  as 
in  air.  A  vertical  pressure  would  increase  its  weight. 

"We  once  heard  two  men  disputing  on  this  subject,  one 
affirming  that  a  stone  did  weigh  less  in  water,  because  he 
had  often  tried  it ;  the  other  affirming  that  it  could  not 
weigh  less,  "  for  you  see,"  said  he,  "  the  stone  is  as  much 
drawn  down  by  gravity  in  the  water  as  out  of  it,  and  the 
water  cannot  lift  any,  when  there  is  more  water  over  it 
bearing  clown  than  under  it  lifting  up." 

In  fact,  on  either  or  all  of  the  principles  affirmed  to  ac- 
count for  the  pressure,  the  change  in  the  gravity  of  the 
stone  cannot  be  explained.  It  is  true  that  the  stone  dis- 
places a  quantity  of  water  equal  to  its  bulk,  but  this  fact 
neither  increases  nor  diminishes  the  force  with  which  the 
earth  attracts  it.  What  is  the  action  of  the  surrounding 
water  ?  How  does  it  press  on  the  stone  ?  Downward 
only  ?  Surely  not ;  "  fluids  press  equally  in  every  direct- 
ion." Equally  on  all  sides?  Then  the  "opposite  dead 
pressures"  must  entirely  neutralize  each  other,  and  have 
no  effect  whatever.  The  decreased  weight  of  the  stone  can 
be  accounted  for  only  on  some  new  principle. 


156  OUTLINES    OF   A    SYSTEM    OF 

We  will  bring  the  pressure  of  water  to  an  infallible  test, 
that  of  our  sense  of  touch,  —  our  honest  perceptions  which 
favor  no  theory  whatever.  Immerse  the  hand  in  water ; 
in  the  act  of  immersion  pressure  is  felt,  for  the  water  is 
moved  by  the  introduction  of  the  hand,  but  when  it  is  at 
rest  in  the  water  not  the  least  pressure  is  experienced. 
Place  the  hand  near  a  small  orifice  from  which  water  is 
issuing,  and  pressure  will  be  felt  because  there  is  a  motion  of 
the  water.  Stop  the  orifice  with  the  palm  of  the  hand,  and 
there  is  no  pressure  ;  for  the  water  has  ceased  to  flow. 

We  now  pass  to  the  consideration  of  that  action  of  fluids 
which  is  called  the  hydrostatic  paradox,  —  an  increase  of 
pressure  which  is  not  in  proportion  to  the  force  applied,  but 
is  in  proportion  to  the  surface  of  the  pressing  fluid.  A 
multiplication  of  pressure  is  apparently  produced, —  an 
effect  greater  than  the  cause,  —  by  some  supposed  myste- 
rious "  principle  of  fluidity  "  applied  force  in  some  cases 
increases  its  power  according  to  the  extent  of  the  surface 
against  which  it  acts. 

It  is  said  that  "  the  true  laws  of  the  equilibrium  of  fluids 
were  discovered  by  Archimedes,  and  rediscovered  by  Galileo 
and  Stevinus,  the  intermediate  time  having  been  occupied 
by  a  vagueness  and  confusion  of  thought  on  physical  sub- 
jects." The  doctrine  is  that,  as  a  fluid  is  a  body,  the  par- 
ticles of  which  have  a  perfect  intermobility,  "  therefore  all 
pressure  exerted  on  one  part  is  transferred  to  all  other 
parts."  Stevinus  deduced  from  this  principle,  that  the 
pressure  on  the  bottom  of  a  vessel  filled  with  fluid,  may  be 
greater  than  the  whole  weight  of  the  fluid.  And  it  is  also 
deduced,  that  the  pressure  may  diverge,  and  may  be  multi- 
plied in  every  direction.  Pascal  shows,  in  his  Treatise  on 
the  Equilibrium  of  Fluids,  "  that  a  fluid  inclosed  in  a  vessel 


MECHANICAL  PHILOSOPHY.  157 

necessarily  presses  equally  in  all  directions  by  imagining 
two  pistons,  or  sliding  plugs,  applied  at  different  parts,  the 
surface  of  one  being  a  hundred  times  greater  than  the 
other ;  it  is  clear  that  the  force  of  one  man  acting  at  the 
first  piston,  will  balance  the  force  of  one  hundred  men  act- 
ing at  the  other."  And  therefore  he  concludes  that,  "  a 
vessel  full  of  water  is  a  machine  which  will  multiply  force 
to  any  degree  we  choose." 

The  apparent  multiplication  of  pressure  is  indeed  a  diffi- 
cult subject  to  grasp  or  comprehend.  The  explanations 
given  of  the  facts  are  far  from  being  clear.  This  seems  to 
be  admitted  ;  for,  as  Whewell  remarks,  "  there  is  a  difficulty 
of  holding  fast  this  idea  of  fluidity.  Even  at  this  day,  men 
of  great  talents  not  unfamiliar  with  the  subject,  sometimes 
admit  in  their  reasonings  an  oversight  or  fallacy  with  regard 
to  this  point.  The  importance  of  the  idea  when  clearly 
apprehended  and  securely  held  may  be  judged  of  from  this, 
that  the  whole  science  of  hydrostatics,  in  its  most  modern 
form,  is  only  the  development  of  this  idea."  But  has  all 
"  vagueness  and  confusion  of  thought "  on  this  subject 
passed  away  ?  Is  it  now  clearly  understood  how  there  can 
be  an  equal  pressure  in  every  direction,  and  at  the  same 
time  the  pressure  be  increased  according  to  depth,  and 
again  multiplied  according  to  surface  ? 

The  facts  which  are  supposed  to  prove  the  multiplication 
of  pressure  in  fluids  are,  the  elevation  of  a  great  weight  by 
a  less  weight  of  water,  as  in  the  hydrostatic  -paradox,  —  the 
bursting  of  a  full  cask  by  the  pressure  of  a  very  small  quan- 
tity of  water  poured  into  a  long  tube  inserted  in  it,  —  and 
the  floating  of  bodies  in  water  of  less  weight  than  the  mass 
that  is  buoyed  up. 

The  hydrostatic  paradox,  as  it  is  called,  may  be  exhibited 

14 


158  OUTLINES    OF   A    SYSTEM    OF 

in  the  following  manner :  Insert  a  long  slender  tube  into  a 
cylinder  with  a  movable  piston  ;  pour  water  into  the  tube, 
and  the  piston  will  be  elevated  by  it ;  if  the  tube  holds  only 
a  pound  of  water,  and  has  an  area  only  one  hundredth  part 
as  great  as  that  of  the  piston,  the  pound  of  water  poured 
into  the  tube  will  elevate  a  hundred  pounds  placed  on  the 
piston.  The  same  action  is  shown  in  the  Bramah  press,  by 
which  a  great  pressure  is  produced  by  gradual  increments 
of  force,  from  water  driven  into  a  large  cylinder  by  a  small 
forcing-pump. 

The  explanation  which  is  usually  given  of  these  facts  is, 
"  that  as  the  pressure  of  the  particles  of  fluid  is  equally  dis- 
tributed among  themselves,  so  external  force  or  pressure  is 
distributed  in  the  same  way."  .  .  "In  the  hydrostatic  press 
an  immense  accumulation  of  force  is  brought  to  bear  upon  a 
particular  point,  by  pressure  applied  by  a  small  column  of 
water  reacting  upon  a  large  mass  placed  on  the  surface  of 
the  piston."  This  explanation  is  hardly  more  than  a  recital 
of  the  facts  ;  how  or  why  the  small  column  of  water  should 
react  with  a  force  proportional  to  the  surface  against  which 
it  is  applied  is  not  in  the  least  explained. 

The  fact  that  the  weight  or  pressure  of  one  pound  of  water 
may  be  made  to  produce  a  pressure  equal  to  that  of  a  hun- 
dred or  a  thousand  pounds,  is  in  reality  no  more  paradoxical 
than  that  one  pound  on  the  long  arm  of  a  lever  should 
balance  a  greater  weight  on  the  short  arm.  Its  action  is 
similar  to  that 'of  other  mechanical  powers.  There  is  no 
increase  or  multiplication  of  the  applied  force.  The  descent 
of  every  pound  of  water  gives  a  spare  force  of  descent  suffi- 
cient for  the  elevation  of  a  pound  weight.  It  will  raise  a 
pound  to  the  same  height  from  which  it  fell,  or  one  hundred 
pounds  T<Ju  of  the  same  height. 


MECHANICAL   PHILOSOPHY.  159 

But  the  force  with  which  the  weight  is  raised  depends  also 
in  part  on  the  area  of  the  surface  of  the  piston.  It  is  equiv- 
alent to  the  force  of  a  descending  column  with  an  area  equal 
to  that  of  the  piston.  That  is,  the  weight  is  raised  with  a 
force  as  great  as  if  the  area  of  the  descending  column  were 
equal  to  its  own,  while  the  extent  of  the  elevation  is  propor- 
tional to  the  volume  of  the  water  which  descends.  The 
extent  of  the  area  of  the  descending  column  does  not  change 
the  force  of  ascent  of  the  column  acted  upon  ;  whether  it  is 
of  one  inch  or  ten  inches  area,  the  effect  produced  is  the 
same.  This  constitutes  the  paradox,  and  it  is  this  fact 
which  requires  explanation. 

We  consider  this  fact  as  strong  proof  of  the  correctness 
of  our  hypothesis  regarding  the  nature  of  the  molecular 
action  of  fluids.  Every  volume  of  water  has  its  molecular 
force  equally  diffused  through  it.  This  force  must  of  course 
be  the  same  in  the  cylinder  as  in  the  tube,  because  from 
their  connection  they  form  one  volume,  while  without  the 
connection  the  force  would  be  different  in  the  two  columns, 
on  account  of  their  differing  depths.  The  molecular  force  due 
to  the  greater  depth  of  the  long  column  is  diffused  through 
the  less  depth  of  the  water  in  the  cylinder.  And,  being 
equally  diffused  through  this  body  of  water,  its  action  is  of 
course  in  proportion  to  the  area  of  the  water.  The  abnor- 
mal molecular  action  of  the  shorter  column  comes  from  the 
equal  diffusion  of  the  normal  force  of  the  longer  column,  and, 
being  abnormal  in  the  shorter,  it  is  converted  into  progress- 
ive motion.  Of  course,  the  force  of  the  progressive  motion 
acts  upon  the  whole  surface  of  the  piston  against  which  it 
is  applied. 

We  will  endeavor  further  to  explain  this  idea.  In  the 
long  slender  tube  the  force  of  molecular  action  is  in  propor- 


160  OUTLINES    OF   A    SYSTEM    OF 

tion  to  the  depth  of  the  water  that  it  contains,  but  it  equally 
diffuses  itself  in  the  water  of  the  cylinder ;  this  diffusion 
gives  an  abnormal  force  for  the  depth  in  the  cylinder,  and 
it  is  therefore  changed  into  progressive  motion,  which  is  the 
force  for  elevation.  In  other  words,  it  is  the  height  of  the 
column  which  determines  the  force  of  the  pressure,  and  the 
quantity  of  water  falling  which  determines  the  extent  of  the 
elevation.  The  reason  that  the  force  of  elevation  is  in  pro- 
portion to  the  area  of  the  surface  of  the  water  which  lifts 
the  piston,  is  that  the  force  of  molecular  action  which  is 
ohanged  into  progressive  motion  is  determined  by  this  area. 
The  idea  may  be  illustrated  by  comparing  the  molecular 
force  to  spiral  springs  placed  beneath  the  piston,  the  num- 
ber of  the  springs  being  determined  by  the  extent  of  the 
surface  against  which  they  are  placed  ;  of  course,  the  larger 
the  surface,  the  greater  the  number  of  the  springs  in  action 
under  it.  Hence,  "  the  force  of  one  man  may  be  made  to 
balance  that  of  a  hundred  men  ; "  for  the  "  reaction"  is  the 
joint  force  of  the  one  hundred  and  one  men  equally  dis- 
tributed. And  hence  it  is,  that  "  not  only  does  the  pressure 
diverge,  but  is  in  all  directions  exactly  equal,  an  equal 
extent  of  the  fluid  being  taken." 

It  has  also  been  deduced  from  this  idea,  that,  if  any  fluid 
in  a  cylinder  be  pressed  by  a  piston,  the  force  which  moves 
the  piston  bears  with  the  same  power  on  every  part  of  the 
surface  of  the  cylinder.  For  instance,  if  the  area  of  the 
piston  is  one  foot,  and  it  is  acte.d  upon  with  a  force  of  one 
hundred  pounds,  and  the  cylinder  has  an  area  of  eight  feet, 
the  one  hundred  pounds  of  pressure  would  be  multiplied  into 
eight  hundred  pounds,  to  give  the  one  hundred  pounds  press- 
ure to  each  foot  of  the  cylinder.  But  it  is  not  so.  The 
one  hundred  pounds  force  is  not  in  the  least  increased  by 


MECHANICAL    PHILOSOPHY.  161 

the  size  of  the  cylinder,  and  is  equally  distributed  over  the 
whole  surface.  The  mistake  has  arisen  from  the  fact,  that, 
if  the  cylinder  is  opened  at  any  part,  there  will  the  whole 
force  concentrate  itself;  and  because  it  can  always  be 
brought  to  any  one  point,  it  has  been  supposed  that  it  acts 
with  its  whole  force  at  every  point  at  once.  The  molecular 
force  is  converted  into  progressive  motion  only  where  it  acts 
against  that  which  is  movable  ;  it  exerts  itself  where  there 
is  room  for  motion.  When  confined,  the  force  is  equally 
distributed  throughout  the  containing  vessel ;  when  suffered 
to  escape,  its  whole  strength  is  transferred  to  the  place 
where  there  is  room  for  motion.  Tap  the  cylinder  at  any 
part  of  its  surface,  and  thence  the  fluid  issues  with  the  force 
which  theory  assigns.  Let  the  boiler  of  a  steam-engine 
burst,  and  at  the  rent  will  issue  the  force  which  theory  has 
made  present  at  every  part.  The  belief,  however,  may 
have  had  a  good  practical  result.  The  mechanic,  on  its 
assumption,  gives  to  his  cylinders  a  strength  in  every  part 
capable  of  sustaining  the  whole  pressure.  The  yielding  of 
any  part  of  the  containing  vessel  concentrates  the  force  at 
this  point  of  comparative  weakness,  where  the  molecular 
action  of  the  fluid  can  change  itself  into  progressive  or  con- 
sentaneous motion.  The  force  applied  is  neither  increased 
nor  diminished  by  the  extent  of  surface  against  which  it 
acts.  It  is  an  invariable  quantity,  and  is  equally  distributed 
throughout  the  containing  vessel. 

It  has  been  a  matter  of  great  surprise  to  practical  me- 
chanics, that  steam-boilers  have  continued  to  work  safely, 
when  worn  so  thin  that  it  appeared  impossible  that  they 
should  bear  the  pressure  which  theory  assigned.  It  was 
recently  mentioned  to  me  by  a  friend,  a  gentleman  of  great 
practical  experience,  that  he  had  just  examined  the  boilers 

14* 


162  OUTLINES   OF  A   SYSTEM   OF 

of  a  very  powerful  engine,  which  had  been  taken  out  for  re- 
pairs, and  was  exceedingly  astonished  to  find  them  so  worn, 
so  much  corroded,  that  in  some  places  he  could  indent  them 
with  a  slight  pressure. 

The  force  of  molecular  action,  however,  will  not  account 
for  the  buoyancy  or  floating  of  bodies.  The  water  around 
them  is  of  equable  depth  ;  there  is  no  confinement  or  unequal 
pressure  to  produce  an  increased  molecular  action  in  any 
one  part  of  the  volume  of  water.  The  molecular  force  exists 
in  its  normal  state  as  the  counterpart  or  complement  of  the 
rotative  force.  Nor  is  buoyancy  produced  by  the  gravitat- 
ing power  ;  for,  as  before  observed,  bodies  will  float  in  water 
of  less  weight  than  themselves.  Place  one  cup  within 
another  so  that  their  surfaces  will  be  nearly  in  contact ; 
pour  between  them  a  little  water,  not  one  half  as  much 
as  the  weight  of  the  inner  cup,  and  the  cup  will  be  lifted, 
and  will  float.  It  is  a  perfectly  established  fact,  that  ships 
do  not  require  to  float  them  a  quantity  of  water  equal  in 
weight  to  themselves.  The  water  in  repairing-docks,  for 
instance,  may  be  far  less  in  weight  than  the  aggregate 
weight  of  the  floating  ships.  This  fact  is  in  direct  opposi- 
tion to  the  law  of  gravitation.  It  cannot  be  reconciled 
with  it ;  for  the  greater  weight  should  be  drawn  down,  and 
should  displace  the  less  weight.  Even  in  the  paradox  the 
gain  of  force  is  apparent  only  ;  it  is  like  the  action  of  the 
lever ;  a  larger  weight  is  raised  only  in  proportion  to 
the  change  of  level  of  a  smaller  weight,  the  quantity  of 
motion  being  the  same  in  both.  By  no  mechanical  contriv- 
ance, whether  it  act  on  fluids  or  on  solids,  can  there  be  a 
positive  gain  of  force.  A  pound  cannot,  by  its  pressure  or 
by  its  fall,  sustain  at  or  lift  to  its  own  level  more  than  a 
pound. 


MECHANICAL    PHILOSOPHY.  163 

If  there  is  a  gravitating  power,  it  must  act  on  the  same 
mass,  at  the  same  distance  from  the  centre  of  attraction, 
with  uniform  intensity.  A  cubic  foot  of  water  will  invaria- 
bly be  acted  upon  with  the  same  power.  In  fact,  a  measure 
of  water  forms  the  standard  of  weight.  Knowing  therefore 
the  weight  of  a  body  to  be  lifted  up,  or  to  be  held  sus- 
pended, the  quantity  of  water,  which  would  be  drawn  down 
with  sufficient  force  to  bury  up  the  mass  immersed  in  it, 
could  be  exactly  calculated.  The  weight  of  the  water 
would  measure  its  pressure,  —  its  effective  force,  —  its  ele- 
vating capacity.  The  extent  of  surface  against  which  it 
acted  could  not  alter  its  efficacy.  If,  therefore,  in  the  phe- 
nomena of  buoyancy,  the  heavier  mass  goes  up  or  remains 
up,  and  the  lighter  goes  down  or  remains  down,  gravitation, 
acting  either  directly  or  indirectly,  cannot  be  the  cause  or 
principle  by  which  buoyancy  is  produced. 

It  is  well  known  that  the  displacement  by  any  floating 
body,  a  ship,  for  instance,  of  a  quantity  of  water  equal 
to  its  own  weight,  is  the  necessary  condition  of  its  buoyancy. 
But  the  displacement  of  the  water  is  not  the  cause  of  the 
buoyancy.  There  is  no  virtue  or  efficacy  in  the  place  from 
which  the  water  is  excluded.  The  pressure  which  gives 
support  must  be  outside ;  it  must  be  in  the  water  around 
the  ship.  If  it  is  supported  by  the  gravitation  of  the  water, 
by  its  pressure  against  the  ship,  the  question  is,  on  what 
principle  does  the  pressure  act  ?  The  extent  of  the  pressure, 
as  we  have  seen,  is  not  determined  by  the  quantity  of  the 
surrounding  water.  That  may  be  more  or  less.  Nor  by 
the  depth  of  the  space  in  water  occupied  by  the  floating 
body  ;  for  it  may  be  wide  and  shoal,  or  narrow  and  deep, 
and  yet  the  quantity  of  water  displaced  be  the  same.  Nor 
is  the  pressure  determined  by  the  extent  of  surface  exposed 


164  OUTLINES   OF  A   SYSTEM   OF 

to  it.  Bodies  of  different  surfaces  may  yet  exclude  the 
same  quantity  of  water.  If  the  pressure,  therefore,  is  deter- 
mined neither  by  the  quantity  of  water,  nor  by  its  depth, 
nor  by  the  extent  of  surface  presented  to  it,  gravitation  is 
not  the  cause  of  buoyancy. 

The  fact  of  buoyancy  is,  we  think,  susceptible  of  explana- 
tion on  our  principles.  We  will  suppose  that  a  vessel  con- 
tains one  hundred  pounds  of  water,  and  that  there  floats  in 
it  a  block  of  wood  weighing  two  hundred  pounds.  We  will 
mark  the  level  of  the  water.  Take  out  the  wood  and  pour 
in  two  hundred  pounds  of  water,  and  the  level  remains  as 
before ;  the  water  added,  or  rather  two  hundred  pounds  of 
water,  occupies  the  place  of  the  wood.  It  acts  and  is  acted 
upon  just  as  the  wood  acted  and  was  acted  upon.  It  is  in 
the  place  of  the  wood  ;  that  which  supported  wood  now 
supports  water.  Enlarge  the  vessel,  and  pour  in  water 
enough  to  make  the  level  the  same  as  before.  The  two  hun- 
dred pounds  of  water  or  of  wood  retain  the  same  place  with 
a  greater  thickness  of  the  strata  at  the  sides.  And  reverse 
it,  —  narrow  the  vessel,  and  take  out  water,  —  the  wood  floats 
as  before.  The  support  neither  of  the  water  nor  of  the 
wood  was  owing  to  the  quantity  of  water  around  it.  The 
floating  body  then  does  not  remain  suspended  from  the 
weight  of  the  water  in  which  it  floats.  There  is  no  tendency 
in  the  water  to  crowd  it  out  of  its  place,  nor  any  to  hold  it 
in  its  place.  A  floating  body  has  no  tendency  to  sink  or  to 
rise.  It  is  not  attracted  downwards.  It  rests  self-poised. 
It  preserves  its  level  because  it  has  the  rotative  force  of  its 
level ;  it  floats  because  the  rotative  energy  is  equally  diffused 
through  itself  and  the  water.  A  ship  has  no  weight  on  the 
water ;  she  does  not  bear  upon  it ;  the  hand  placed  between 
her  and  the  water  would  not  be  in  the  least  compressed. 


. 


MECHANICAL    PHILOSOPHY.  165 

She  is  not  attracted  downward  by  gravitation,  nor  is  the 
water  attracted  upward  against  her.  But  if  she  descend 
from  her  level,  she  has  force  of  descent,  as  have  all  falling 
bodies.  She  then  bears  upon  the  water,  moving  it  by  her 
force  of  descent.  The  hand  under  her  would  then  feel  a 
pressure.  She  floats  as  her  weight  of  water  would  float. 

Her  motion,  her  rise  and  fall,  is  an  oscillation  which 
corresponds  to  the  oscillation  of  the  waves.  This  vertical 
motion  is  the  transfer  and  re  transfer  of  rotative  force,  her 
mean  level  of  rotation  being  still  preserved.  The  wave, 
rising  by  force  robbed  from  the  passing  wind,  transfers  force 
to  the  ship,  which  also  rises  ;  this  force  expended  in  the  su- 
perior level,  she  pauses  a  moment,  and  then  falls  with  accel- 
erated force,  till  again  met  by  the  rising  water,  —  ever  float- 
ing as  the  body  of  water  whose  place  she  takes  would  float. 

A  picture  is  beautiful  because  it  bears  the  impress  of  the 
artist,  —  because  on  the  canvas  has  been  laid  the  idea  of 
his  mind,  —  because  by  the  drawing,  coloring,  and  com- 
bination, he  declares  the  thought  which  engrossed  him  as 
he  sat  at  the  easel.  Thus  nature  is  beautiful,  when  in  ad- 
dition to  the  mere  outline,  the  form,  the  color,  which  the 
eye  takes  in,  the  mind  perceives  also  the  characters,  the 
language  w'hich  declares  the  power  and  wisdom  by  which  it 
was  constituted. 

In  this  point  of  view  how  beautiful  is  a  ship,  borne  along 
on  the  wings  of  the  wind !  She  is  not  a  mere  combination 
of  wood  and  iron,  of  cordage  and  canvas,  but  she  represents 
and  proclaims  to  us  unseen  force,  —  the  laws  of  the  elements. 
Hence  the  sailing  of  a  ship  becomes  of  absorbing  interest ; 
she  is  full  of  life,  upborne  by  innate  energy,  as  she  bends  to 
the  breeze,  leaps  joyously  over  the  waves,  or  sternly  defies 
the  power  of  the  storm, 


166  OUTLINES   OF   A   SYSTEM   OF 

"We  referred,  in  the  first  part  of  this  chapter,  to  the  impos- 
sibility of  explaining  what  is  called  specific  gravity,  accord- 
ing to  the  theory  of  the  gravitation  of  fluids.  The  weight 
of  any  mass  of  matter  is  supposed  to  measure  exactly  the 
degree  of  attraction  which  the  earth  exercises  upon  it. 
Why  should  the  attracting  force  be  lessened  when  the  body 
is  placed  in  water?  If  an  immersed  stone  were  pressed 
down  by  the  water,  its  weight  would  be  increased  by  the 
immersion  ;  or,  if  the  fluid  pressed  upon  it  equally  in  every 
direction,  its  weight  would  remain  the  same  as  before.  If 
the  pressure  upon  it  were  upward  only,  its  loss  of  weight 
might  be  accounted  for.  We  explain  the  loss  of  weight  of 
a  body  immersed  in  water  in  the  following  manner :  The 
force  which  gives  certain  degree  of  motion  to  a  body  is  mea- 
surable by  the  quantity  of  matter  that  the  moving  body  con- 
tains, each  atom  receiving  its  due  proportion.  It  follows 
that  the  force  required  for  any  determinate  degree  of  velo- 
city depends,  not  on  the  volume  of  the  body,  but  on  its 
density.  The  force  required  to  move  any  body,  therefore, 
is  in  proportion  to  the  quantity  of  matter  which  it  contains, 
not  to  its  bulk, —  to  its  atomic  structure,  not  to  the  space 
that  it  occupies.  The  force  needed  for  the  motion  of  a  body 
in  any  direction  being  ascertained,  the  quantity  of  matter 
in  the  body  relative  to  the  space  that  it  occupies  can  also 
be  ascertained. 

The  force  of  rotation  in  bodies  at  the  same  level  being  in 
direct  proportion  to  the  quantity  of  matter  which  they  contain, 
all  bodies,  large  or  small,  dense  or  porous,  in  falling  having 
spare  force  proportioned  to  their  quantity  of  matter,  should 
move  downward  with  equal  velocity  without  reference  to 
their  bulk  in  relation  to  density.  This  is  the  case  with 
bodies  falling  in  a  vacuum  ;  a  feather  falls  as  quickly  as  a 


MECHANICAL    PHILOSOPHY.  167 

bullet.  But  in  bodies  falling  through  the  atmosphere,  the 
greater  the  bulk  relative  to  density,  the  less  is  the  compar- 
ative velocity,  and  in  falling  through  water  the  retardation 
of  velocity  is  greatly  increased.  These  results  are  usually 
thus  expressed  :  "  The  greater  the  bulk  of  the  body  com- 
pared with  the  matter  it  contains,  the  more  the  air  or  water 
resists  the  fall,  and  thereby  decreases  the  velocity."  Throw 
away  the  consideration  of  velocity  which  is  an  effect,  and 
the  statement  is  more  simple.  In  a  vacuum,  the  force  of 
descent  relative  to  the  matter  is  the  same  in  all  bodies,  large 
or  small,  light  or  heavy  ;  in  the  atmosphere  a  part  of  the 
force  derived  from  change  of  level  is  transferred  to  the  air, 
and  there  remains  less  force  for  descent ;  in  the  water  a 
still  greater  part  is  transferred,  and  still  less  force  remains 
for  descent.  The  force  transferred  to  the  air  is  exactly  that 
degree  which  is  required  to  move  a  volume  of  air  of  the  bulk  of 
the  moving  body,  through  the  same  extent  of  space,  and  with 
the  same  velocity  as  that  of  the  falling  body.  So  the  force 
transferred  to  the  water  is  that  which  is  requisite  to  move 
an  equal  bojly  of  water  through  the  space  described  by  the 
fall,  and  with  the  velocity  of  the  fall.  In  the  descent  of  a 
body,  therefore,  through  air  or  through  water,  it  moves,  in 
opening  its  path,  a  volume  of  the  medium  through  which  it 
passes,  of  its  own  bulk,  and  with  its  own  speed.  Its  loss  of 
force  therefore  measures  the  weight  of  its  own  bulk  of  the 
fluid  through  which  it  passes.  The  water  or  air  moved 
may  be  moved  upward,  downward,  or  sideways  ;  but  the 
imparted  force  is  exactly  of  that  intensity,  which  would  have 
raised  a  volume  of  air  or  water  of  its  own  bulk  as  high  as 
the  level  from  which  the  falling  body  descended.  Hence 
the  retardation  of  the  fall  measures  the  weight  or  density  of 
the  medium,  and  conversely  the  density  of  a  stone  is  ascer- 


168  OUTLINES    OF   A    SYSTEM    OF 

tained  by  being  weighed  in  water.  This  is  an  unvarying 
principle.  The  seeming  discrepancy  in  the  fact  that  the 
fall  of  bodies  of  great  extension  of  surface  as  compared  with 
their  density  is  of  less  velocity,  as  in  the  case  of  the  para- 
chute, is  because  a  mass  of  air  must  necessarily  fall  with 
it,  as  if  the  air  and  parachute  constituted  one  falling  body. 
If  a  mass  of  wood  falls  in  a  vacuum,  its  motion  downward 
is  with  all  the  force  derived  from  its  change  of  level.  If  in 
air,  it  will  fall,  though  with  less  force  ;  for  the  force  derived 
from  its  descent  is  sufficient  to  give  it  its  own  motion,  and 
to  raise  a  quantity  of  air  equal  to  its  own  volume.  In  water, 
however,  it  cannot  fall,  for  the  force  that  would  be  acquired 
by  its  descent  to  a  lower  level,  is  not  sufficient  to  move  a 
quantity  of  water  of  its  own  bulk.  In  the  space  occupied 
by  the  wood,  the  quantity  of  matter  is  less  than  it  would  be 
in  the  same  space  if  filled  with  water.  The  force  of  the  de- 
scent of  the  wood  is  in  proportion  to  its  own  density,  —  to  its 
own  quantity  of  matter.  In  order  to  descend,  it  must  open 
its  path.  It  must  transfer  enough  of  its  force  to  move  out 
of  the  way  the  surrounding  water,  —  not  a  quantity  at  once 
equal  to  its  own  volume,  but  a  quantity  proportional  to  its 
degree  of  descent.  If  the  water  of  equal  bulk  contains 
more  matter,  the  spare  force  of  the  descent  of  the  wood  is 
not  sufficient  for  any  degree  of  the  elevation  of  water  ;  of 
course,  there  can  be  no  descent  of  the  wood.  It  can  only 
float.  Buoyancy  depends,  therefore,  on  inferior  density 
compared  with  the  medium  in  which  it  is  placed,  not  on  the 
quantity  of  the  medium.  If  a  body  placed  in  water  contains 
more  matter  than  the  same  volume  of  water,  it  falls  or 
sinks.  If  of  equal  density  with  the  water,  it  floats  in  it  at  any 
distance  from  its  surface.  The  case  is  the  same  in  air,  or 
in  any  other  medium.  By  weighing  a  body  first  in  a  vacuum, 


MECHANICAL  PHILOSOPHY.  169 

and  afterwards  in  air.  its  comparative  density  can  be  ascer- 
tained. In  the  floating  of  a  ship,  partly  in  the  air,  partly 
in  the  water,  her  density  is  measured  by  both,  that  is,  her 
degree  of  specific  weight  gives  her  place  between  the  two 
elements.  Lighter  than  her  bulk  of  water,  heavier  than  her 
bulk  of  air,  she  neither  sinks  nor  rises,  but  remains  sus- 
pended at  the  junction,  at  the  meeting  surfaces,  of  the  ocean 
and  of  the  atmosphere. 

It  will  be  seen  that  this  explanation  is  somewhat  similar 
to  that  which  is  usually  given.  Those  who  believe  in  ter- 
restrial attraction  do  not  think  that  a  stone  is  less  attracted 
when  in  water  ;  they  attribute  its  loss  of  weight  to  its  dis- 
placement of  water,  because  the  loss  is  measured  by  the 
weight  of  the  quantity  of  water  that  would  fill  the  space 
occupied  by  the  stone.  But  it  is  not  what  a  stone  excludes, 
but  the  quantity  of  matter  which  it  contains,  which  deter- 
mines its  weight,  and  its  atoms  remain  the  same  whether  it 
is  weighed  in  water  or  in  air.  An  explanation,  therefore, 
based  upon  the  theory  of  gravitation,  cannot  refer  to  the 
quantity  of  water  excluded  by  the  stone,  for  the  force  with 
which  it  is  attracted  is  not  lessened  thereby.  The  stone  and 
all  that  it  contains,  that  is,  all  that  is  interior  to  the  medium, 
is  unchanged  by  the  medium.  Under  the  theory  of  gravi- 
tation, there  can  be  no  cause  for  the  loss  of  weight  except 
the  action  of  that  which  is  exterior  to  the  stone  ;  in  other 
words,  the  degree  and  kind  of  the  pressure  upon  it. 

But  outside  there  is  no  conceivable  action  of  the  water 
induced  by  its  gravity,  that  can  possibly  result  in  a  loss  of 
weight  of  the  stone  equal  to  the  weight  of  excluded  water. 
Gravitation,  we  repeat  the  idea,  pressing  the  water  down- 
ward upon  the  stone,  will  not  give  the  result ;  gravitation, 
pressing  the  water  against  the  stone  equally  in  every  direc- 

15 


170  OUTLINES   OF  A   SYSTEM   OF 

tion,  will  not  'give  it ;  nor  will  a  current  of  water  moving 
from  above  to  beneath  the  stone,  for  under  the  law  of  grav- 
itation it  does  not  require  a  force  equal  to  the  weight  of  a 
given  quantity  of  water  to  move  this  water  when  under 
water.  For  a  reason  of  the  loss  of  weight,  therefore,  all, 
whatever  be  the  theory,  are  compelled  to  go  from  the  press- 
ure upon  it  to  the  body  itself ;  from  the  action  of  external 
force,  to  the  force  pertaining  to  the  stone  ;  from  the  theory 
of  gravitation,  of  external  attraction,  to  the  force  of  motion. 
Our  theory,  which  gives  place  and  position  to  matter  accord- 
ing to  its  degree  of  rotative  force,  does  not  require  to  be 
changed. 

There  is  indeed  no  reason  to  be  given  under  the  theory 
of  gravitation,  why  a  stone  should  lose  in  weight  the  weight 
of  water  which  would  occupy  its  place.  There  is  nothing  in 
gravitation  by  which  it  can  so  modify  its  action  on  the  sur- 
rounding water,  as  to  make  it  press  upon  the  stone  in  exact 
proportion  to  its  solid  contents.  This  theory,  therefore, 
cannot  explain  specific  gravity  by  the  attraction  of  the  stone, 
or  by  the  attraction  of  the  medium ;  nor  by  any  possible 
combination  of  the  two.  Gravitation  cannot  attract  the 
stone  more  or  less,  or  the  water  more  or  less,  from  the  fact 
that  the  stone  and  water  are  in  contact.  Nor  can  the 
result  be  modified  except  by  mutual  pressure,  and  we  have 
seen  that  the  kind  of  pressure  which  gravitation  induces  is 
totally  inadequate  to  explain  the  phenomena. 

On  the  other  hand,  do  not  we  present  an  intelligible  and 
distinct  explanation  ?  We  consider  force  as  having  an 
actual  existence.  In  the  case  of  a  body  falling  through 
water,  we  show  the  source  of  the  power  by  which  it  moves, 
the  force  of  descent  from  a  higher  level,  and  we  trace  out 
the  division  of  this  force  in  action.  There  is  so  much  less 


MECHANICAL    PHILOSOPHY.  171 

in  action  upon  the  stone,  as  is  transmitted  for  the  motion 
of  the  water  necessary  for  the  relative  change  of  place. 
Specific  gravity  weighs  this  force.  Weight  is  the  force  of 
motion.  It  is  not  an  incomprehensible  abstraction ;  it  is 
not  an  instinct  or  tendency  of  matter  to  approach  matter. 
There  is  no  weight  without  motion,  and  the  cause  of  motion 
is  the  force  present  in  the  moving  body.  Has  not  philosophy 
erred  in  referring  to  other  matter  as  the  cause  of  all  motion 
in  matter,  instead  of  looking  where  the  motion  is  for  the 
force  which  produces  it  ?  Why  may  it  not  be  supposed 
that  matter  has  power  to  move  itself,  as  well  as  that  it  can 
induce  motion  in  other  matter  ? 

As  we  have  before  said,  water  is  elevated  by  receiving  a 
share  of  the  stone's  force  of  descent ;  in  other  words,  water 
goes  up  because  the  stone  goes  down.  Often,  however, 
matter  descends  because  other  matter  ascends.  We  take 
a  balloon  as  an  instance  of  this  converse  action.  It  is  sup- 
posed that  a  balloon  goes  up  from  the  superior  weight  of  a 
volume  of  air  of  its  own  size,  —  that  it  is  crowded  or  pressed 
out  of  its  place  by  a  fall  of  air  into  its  place.  Can  this 
be  so? 

Air  either  presses  downward  upon  the  balloon,  or  equally 
upon  it  in  every  direction.  As  we  have  before  said,  neither 
nor  both  of  these  pressures  could  produce  elevation.  The 
current  of  air  from  above  downward  is  not  established  until 
the  balloon  has  commenced  its  rise  ;  this  current  is  there- 
fore a  result  of  the  motion,  not  its  cause.  As  water  is  lifted 
by  the  fall  of  a  stone  into  it,  so  air  is  moved  downward  by 
the  ascent  of  a  balloon.  It  is  the  peculiarity  of  construction 
or  of  element  in  the  stone  which  enables  it  to  fall  in  relation 
to  water ;  it  is  the  construction  or  elementary  constitution  of 
the  hydrogen  of  the  balloon  which  causes  its  rise  in  relation 
to  the  atmosphere. 


172  OUTLINES    OF   A    SYSTEM    OF 

This  idea  we  will  illustrate  by  supposing  a  balloon  held 
down  by  a  cord,  and  a  dense  body  of  the  same  size  and  form 
held  up  by  a  cord,  each  producing  the  same  tension  of  the 
cords  which  restrain  their  motion.  They  are  at  rest.  The 
air  presses  on  both  in  the  same  manner  and  with  the  same 
force.  The  "  tendency  "  of  one  to  go  up,  and  of  the  other 
to  go  down,  comes  not  from  the  atmosphere  ;  for  its  pressure, 
being  on  bodies  of  the  same  form  and  size,  is  of  course  the 
same  on  both.  By  drawing  each  of  them  aside,  —  by  giving 
them  an  impulse,  —  they  will  swerve  to  and  fro  as  does  a  pen- 
dulum. The  air  does  not  aid  this  movement,  but  retards  it ; 
for  both  the  swinging  bodies  lose  a  part  of  their  force  of 
motion  by  the  "  resistance  "  of  the  medium  in  which  they 
oscillate.  Does  gravity  cause  this  converse  oscillation,  by 
depressing  one  giving  it  force  for  elevation,  by  elevating  the 
other  giving  it  force  of  depression  ?  When  the  oscillation 
is  suspended,  if  the  cords  which  confine  them  are  cut,  one 
will  commence  its  rise,  the  other  its  fall,  before  a  particle  of 
air  has  moved  in  relation  to  either.  If  we  suppose  two 
equal  receptacles,  one  filled  with  hydrogen  so  that  it  will 
rise,  the  other  with  a  gas  heavier  than  the  atmosphere  so 
that  it  will  fall,  the  external  air  bearing  on  each  with  the 
same  pressure  because  they  are  of  equal  size  and  similar 
shape,  we  cannot  avoid  the  conclusion  that  the  cause  of  the 
rise  of  the  one  and  the  fall  of  the  other  depends  not  on  the 
surrounding  medium,  but  on  a  positive  difference  in  the 
structure  or  character  of  the  inclosed  gases. 

It  is  impossible  to  suppose  that  gravitation  attracts  the 
one  and  repels  the  other,  or  that  it  modifies  the  pressure  of 
the  air  around  the  one  to  favor  its  ascent,  and  around  the 
other  to  favor  its  descent.  The  interchange  of  force  from 
the  medium  to  the  moving  body,  or  from  the  moving  body 


MECHANICAL  PHILOSOPHY.  173 

to  the  medium,  is  a  result  of  motion ;  it  is  not  the  impelling 
cause. 

The  cause  of  all  motion  is  the  presence  of  force  in  the 
moving  body.  The  degree  of  rotative  force  determines  the 
level  of  rotation.  For  instance,  hydrogen  at  its  formation, 
at  the  commencement  of  its  separate  existence,  possesses  an 
intense  molecular  force.  If  unconfined  this  force  changes 
into  progressive  motion,  and  it  rises,  exhausting  its  atomic 
intensity  in  rotation  at  the  higher  level.  Its  power  of  ele- 
vation, and  the  height  of  its  rise,  depend  therefore  on  the 
degree  of  the  present  force. 

But  the  question  returns,  what  causes  some  bodies  to 
ascend  and  others  to  descend  relatively  to  the  medium  in 
which  they  move  ?  Why  does  hydrogen  change  its  force 
of  molecular  action  into  progressive  motion  at  the  higher 
level  ?  Why  does  the  stone  give  up  a  part  of  its  rotative 
force  and  descend  ?  In  other  words,  what  is  the  principle 
which  governs  the  degree  of  rotative  force,  which  bodies 
left  free  to  take  their  own  position  will  retain  ? 

We  have  before  noticed  the  fact  that  cohesion  and  chemi- 
cal affinity  both  depend  upon  sympathy  of  molecular  action,  — 
on  the  equality  of  the  diffusion  of  the  present  force.  It  is 
this  which  forms  all  combinations,  and  determines  the  sepa- 
rate existence  of  masses  and  of  volumes.  And  as  the  force 
present  in  each  atom  determines  its  position  in  relation  to 
other  atoms,  in  their  combination  forming  masses,  the  same 
principle  determines  also  the  relative  position  of  the  masses. 

Molecular  action  is  the  counterpart  of  progressive  motion ; 
there  is  a-  normal  ratio  between  them.  The  degree  of  rota- 
tive force  that  any  mass  or  volume  can  retain  if  free  to 
change  its  position,  depends  upon  its  capacity  for  molecular 
action.  This  capacity  depends  upon  atomic  structure,  and 


174  OUTLINES   OF  A   SYSTEM   OF 

atomic  structure  determines  level.  The  fall  or  rise  of 
bodies  relatively  to  each  other,  is  determined  therefore  by 
the  comparative  density  of  the  moving  masses.  One  law 
not  only  governs  combination,  but  also  governs  the  level  of 
rotation. 

Comparative  density,  —  the  quantity  of  matter  relatively 
to  the  space  occupied,  —  in  other  words,  capacity  for  the 
motion  of  its  atoms,  determines  whether  a  body  rises,  or  falls, 
or  remains  suspended,  in  any  medium.  And  as  all  terres- 
trial bodies  move  in  some  medium,  or  move  relatively  to 
other  matter,  it  is  the  distance  between  the  particles  of  a 
body,  —  its  atomic  structure,  —  which  causes  it  to  rise  or  to 
fall,  or  which  gives  it  a  relatively  permanent  position.  The 
force  of  rotation  belonging  to  position  is  not  always  the  nor- 
mal force  of  the  structure  of  the  body.  If,  therefore,  there 
is  space  for  motion,  it  is  moved  upward  or  downward  until 
position  conforms  the  rotative  force  to  the  normal  degree  of 
molecular  force,  which  is  its  counterpart.  The  result  is  the 
formation  of  currents  of  revolving  matter,  in  which  there  is 
an  equality  of  the  diffusion  of  force  in  relation  to  space,  as 
well  as  in  relation  to  density.  The  result  is,  the  sympa- 
thetic motion  of  every  atom  composing  the  world,  —  a  reg- 
ular increase  of  motion  from  its  centre  to  its  outermost 
circle. 

To  unfold  this  principle  as  far  as  it  appears  to  us  dis- 
tinctly conceived,  would  require  a  greater  space  than  can 
be  given  in  this  outline.  It  would  be  out  of  place  also  in 
a  treatise  designed  to  present  only  the  very  first  principles 
of  a  theory.  We  confine  ourselves  therefore  to  the  thoughts 
already  suggested.  A  body  falls  because  it  is  not  sur- 
rounded by  that  medium  for  which  its  atomic  structure  fits 
it ;  it  is  not  in  that  stream  of  revolving  matter  in  which 


MECHANICAL  PHILOSOPHY.  175 

force  is  normally  diffused.  It  falls  when  the  force  gained 
by  descent  is  not  only  sufficient  for  its  downward  motion, 
but  also  sufficient  to  give  the  corresponding  elevation  to  its 
volume  of  the  matter  by  which  it  is  surrounded.  A  body 
rises  under  analogous  conditions,  —  when  it  has  force  not 
only  for  its  own  ascent  to  a  higher  level,  but  enough  to  move 
from  its  path  its  own  volume  of  the  surrounding  matter. 
A  body  rises  or  falls  according  to  its  present  force,  —  accord- 
ing to  its  atomic  structure  or  capacity  for  molecular  action. 

The  equilibrium  of  force,  the  normal  motion  of  matter,  is 
preserved  by  the  resolution  of  the  molecular  into  greater 
progressive  motion,  at  a  superior  altitude,  or  by  the  decrease 
of  rotative  force  by  the  descent  of  a  body.  The  force 
pertaining  to  the  atoms  and  that  pertaining  to  the  mass  are 
thus  brought  into  conformity,  whatever  may  be  the  structure 
of  the  mass  ;  the  great  result  is  harmony  of  motion,  —  the 
equality  of  the  diffusion  of  force. 

The  rise  and  fall  of  bodies,  therefore,  is  but  an  inter- 
change of  place  between  equal  volumes  of  matter.  And, 
while  the  cause  of  the  motion  of  a  body  is  within  itself,  as 
to  the  velocity  and  direction  of  its  motion,  it  depends  upon 
the  medium  through  which  it  moves.  Matter  influences  the 
motion  of  other  matter  only  by  an  interchange  of  force,  — 
by  the  transmission  of  motive  energy  from  one  body  to 
another.  It  is  force  which 

"  Sweeps  through  the  dull,  dense  world,  compelling  there 
All  new  successions  to  the  forms  they  wear." 

Thus  is  the  place  and  position  of  all  things  determined, — 
not  by  the  "  appetite  of  matter"  for  matter,  —  not  by  the 
desire  of  one  fragment  of  the  world  for  the  presence  of 
another  fragment,  —  not  by  mutual  attraction,  —  not  by  a 


176  OUTLINES   OF   A   SYSTEM   OF 

blind  instinct  of  consolidation,  kept  at  times  in  abeyance  by 
an  equally  blind  instinct  of  repulsion.  It  is  by  the  diffusion 
of  force,  giving  the  position  of  every  atom,  that  the  order  of 
the  universe  is  maintained.  Change  is  as  normal  as  per- 
manence,—  fluctuation  as  much  a  phase  of  perfection  as 
stability  itself.  A  solitary  rain-drop  gives  us  a  glimpse  of 
the  law,  which  in  its  action  clothes  the  earth  with  verdure  ; 
the  sudden  shooting  of  a  minute  crystal  into  perfect  sym- 
metry discloses  the  power  which  gives  form  and  cohesion 
to  the  world. 

This  view  carries  us  again  to  the  thought  which  we  have 
before  attempted  to  elucidate,  • — to  our  idea  of  the  unity  of 
force,  —  to  the  oneness  of  that  energy,  which  under  many 
manifestations  constitutes  the  "  Life  of  the  Universe." 
We  hear  it  in  the  rustling  of  the  forest  leaves,  in  the  roar 
of  the  ocean,  in  the  thunder  of  the  storm ;  we  see  it  in 
the  aurora's  arch,  in  the  volcano's  blaze,  in  the  lightning's 
flash ;  we  trace  it  by  the  oscillations  of  the  barometer,  by 
the  tremblings  of  the  magnetic  needle,  by  the  action  of  the 
voltaic  pile ;  we  witness  the  full  majesty  of  its  action  in 
the  motions  of  the  spheres. 

This  thought,  which  resolves  the  powers  which  move  all 
things  above  and  around  us  into  one  and  the  same  force, 
ever  circulating,  ever  inducing  perfection,  never  subsiding 
into  rest,  is  not  a  mere  poetical  •  idea,  a  dream  of  the 
imagination.  The  fact  of  the  unity  of  force,  —  the  identity 
of  its  nature  under  whatever  form  it  may  present  itself,  — 
is  proved  by  the  most  accurate  experiments,  by  the  severest 
tests  of  philosophy.  Fill  a  metallic  plate  with  a  crystalliz- 
ing solution,  place  a  horseshoe  magnet  under  it,  crystalliza- 
tion ensues  immediately,  and  the  line  of  crystals  formed 
writes  down  the  direction  of  the  current  of  magnetic  force. 


MECHANICAL   PHILOSOPHY.  177 

Cohesion,  then,  is  but  one  phase  of  force,  —  symmetry  of 
form  one  of  the  results  of  its  action.  A  rain-drop  falls  be- 
fore us.  We  know  from  the  experiments  of  Farraday  the 
exact  amount  of  force  which  formed  it  from  its  constituent 
gases,  and  by  the  abstraction  of  which  it  will  be  again 
resolved  into  its  elements.  Further,  we  trace  in  its  fall  the 
operation  of  the  same  force  which  gives  its  rotative  and 
revolving  motion  to  the  world. 

For  another  illustration,  we  would  recur  to  the  fact  that 
metallic  bars,  when  cooling  under  certain  conditions,  are 
thrown  into  a  state  of  vibration,  and  emit  a  musical  note 
like  the  sound  of  an  eolian  harp,  and  that  the  same  note  is 
again  heard  from  soft  iron  when  becoming  magnetized. 
Thus  the  poetry  of  science  is  but  the  revelation  of  its  highest 
truths.  Why  should  we  continue  to  regard  the  world's 
beautiful  mystery  with  but  one  pervading  idea,  —  that  of  the 
power  of  matter  to  draw  other  matter  into  contact  with  it  ? 
As  well  might  we  attempt  to  solve  all  the  phenomena  of 
animal  life  by  the  attraction  of  the  particles  of  the  body  for 
one  another,  or  all  the  phenomena  of  thought  by  bodily- 
sensation, —  by  atomic  wisdom. 


CHAPTER  VIII. 


"  HE  SUNG  THE  SECRET  SEEDS  OP  NATURE'S  FRAME  ', 
JlOW  SEAS,  AND  EARTH,  AND  AIR,  AND  ACTIVE  FLAME 
FELL  THROUGH  THE  MIGHTY  VOID,  AND  IN  THEIR  FALL 
WERE  BLINDLY  GATHERED  IN  THIS  GOODLY  BALL." 

Dry  den's  Virgil. 

A  FULL  belief  in  the  attractive  force  of  matter  causes 
every  fact  to  be  seen  through  this  theory  as  a  medium. 
It  therefore  gives  coloring  to  facts  ;  as  it  were,  it  corrects 
observation  ;  it  makes  experiment  conform  to  what  it  has 
previously  determined  ought  to  be  the  result ;  it  asks,  how 
discrepancies  can  be  explained,  not,  —  Can  they  be  explained  ? 

How  different  the  mental  process  in  regard  to  a  new 
theory.  The  question  at  once  changes  its  form.  It  is  now,  — 
Is  it  possible  that  this  theory  can  be  true  in  the  very  face 
of  this  or  that  disagreement  with  observed  facts  ?  In  one 
case,  ingenuity  exerts  itself  in  accounting  for  discrepancies  ; 
in  the  other,  in  discovering  them. 

We  will  refer  to  one  illustration  of  this  idea,  though  it  is 
somewhat  foreign  to  the  immediate  subject  of  the  present 
chapter.  It  is  well  known  that  the  pendulum  alters  its  rate 
over  different  parts  of  the  surface  of  the  earth,  in  the  same 
parallels  of  latitude.  In  different  mines,  too,  it  varies*  at 
the  same  depth.  Of  course,  it  might  be  inferred  that  the 
force  of  gravitation  changes  in  intensity.  But,  according 
to  theory,  gravitation  is  invariable  in  relation  to  the  same 


MECHANICAL    PHILOSOPHY.  179 

quantity  of  matter.  Thence  it  follows,  if  there  be  less 
attraction  at  any  one  point,  that  there  are  caverns  and  hol- 
lows in  the  earth  ;  if  there  be  more,  the  density  of  the 
rocks  near  the  surface  is  far  beyond  the  mean  density  of 
the  earth  ;  or  there  are  "  deflecting  causes  concealed  be- 
neath the  surface  of  the  soil."  Why  the  less  density  of  the 
ocean  does  not  invariably  change  the  rate  of  the  pendulum 
has  not  yet  been  declared.  The  Shechallien  mountain  in 
Scotland  deflects  a  plummet  from  the  vertical  direction, 
and  from  this  swerving  the  mean  density  of  the  earth  has 
been  calculated.  Other  mountains  cause  little  or  no  pertur- 
bation of  the  attractive  force  ;  they  are  therefore  but  hollow 
cones,  —  though  they  may  have  miles  of  height  and  miles  of 
base,  they  are  mere  shells,  —  the  thin  walls  of  extinct  vol- 
canoes !  Volcanic  islands,  on  the  other  hand,  generally 
show  "  an  augmented  intensity  of  the  attraction  of  gravita- 
tion ;  "  where  there  is  an  exception,  it  is  traced  to  the  influ- 
ence of  some  high  land  on  a  neighboring  coast.  Thus  a 
theoretic  uniformity  is  preserved,  whatever  may  be  the 
statement  made  by  facts.  The  mountain  which  swerves  the 
plummet  is  proof  of  the  universal  law  of  the  attraction  of 
matter  ;  that  which  does  not  offers  no  disproof,  —  leads  to 
no  doubt  of  the  general  principle.  It  is  well  that  it  is  so. 
Theories  thus  establish  order,  when  without  them  there 
would  be  confusion.  It  is  better  to  obey  a  provisional  gov- 
ernment, though  it  be  not  destined  to  perpetuity,  than  to  be 
entirely  without  law.  Theories  are  but  steps  in  progress. 
How  painful  the  thought  that  any  present  knowledge  is  the 
highest  that  can  be  attained  ;  that  any  theory  is  the  widest 
reach  of  the  intellect ;  that  in  the  future  there  are  in  store 
for  us  no  further  interpretations  of  the  wisdom  of  God  as 
written  upon  his  works  ! 


180  OUTLINES   OF  A   SYSTEM   OF 

We  return  to  the  examination  of  the  theory  of  the  gravi- 
tation of  fluids.  If  a  tumbler  is  filled  with  water,  a  piece 
of  paper  pressed  over  its  mouth,  and  the  glass  then  in- 
verted, the  water,  instead  of  falling  from  it,  will  remain  sus- 
pended. The  slight  adhesion  of  the  paper  is  sufficient  to 
overcome  the  whole  force  of  the  attraction  of  the  earth  upon 
the  water.  This  is  explained  by  the  pressure  of  the  air 
induced  by  gravitation,  which  is  supposed  to  act  upward 
against  the  paper. 

But,  according  to  the  principles  of  the  gravitation  of  fluids, 
this  effect  could  be  produced  only  when  there  is  no  air  left 
in  the  tumbler  with  the  water.  It  has  been  stated  that,  if 
the  smallest  quantity  of  air  remained,  its  pressure  above  the 
water  would  neutralize  the  pressure  of  the  external  air,  and 
the  water  would  fall.  But  such  is  not  the  fact.  Let  the 
glass  be  one  half,  one  quarter,  one  eighth  full  of  water,  and 
then  inverted  as  before,  the  water  will  remain  suspended 
with  air  over  as  well  as  below  it.  We  have  often  tried  this 
experiment,  and  called  others  to  witness  the  fact,  that  water 
suspended  mid  air,  with  the  same  pressure  above  as  below, 
refuses  to  obey  the  law  of  gravitation. 

Fill  a  long  tin  tube  with  dry  sand,  and  press  on  one  end 
a  piece  of  thin  paper  slightly  moistened  ;  let  the  upper  end 
be  open  so  that  the  pressure  of  the  air  will  act  both  upwards 
and  downwards  upon  the  sand,  and  thus  neutralize  itself  as  in 
the  former  case.  The  sand  will  not  overcome  the  friction 
of  the  sides  of  the  tube  and  the  adhesion  of  the  paper,  and 
will  remain  suspended,  say  two  pounds  of  it,  against  the 
attraction  of  gravitation. 

Here  is  a  case  precisely  analogous  to  that  of  the  water 
suspended  in  the  tumbler.  How  is  it  explained  ?  "  Single 
grains  of  sand  placed  on  a  flat  surface  do  not  begin  to  roll, 


MECHANICAL   PHILOSOPHY.  181 

until  the  heap  is  inclined  between  30°  and  40°,  and  this  is 
the  angle  at  which  pressure  is  exerted,  when  this  motion  is 
resisted  ;  and  the  weight  of  a  pyramid,  whose  sides  are  in- 
clined at  this  angle  is  supported  at  the  base  alone,  whatever 
may  be  the  height  of  the  column  confined  above  it,"  there- 
fore, "  the  paper  supports  the  sand,  though  it  adheres  very 
slightly; "  or,  to  express  the  conclusion  in  other  words,  the 
force  of  the  adhesion  of  the  paper  to  the  edges  of  the  tube, — 
an  adhesion,  which  a  very  slight  force  would  overcome,  —  can 
bear  up  against  the  gravitation  of  several  pounds.  Why 
speak  of  the  angle  at  which  sand  rolls  ?  It  is  not  necessary 
for  the  earth  to  roll  the  sand  in  order  to  bring  it  down. 

Here  are  several  pounds  of  sand  supported  by  the  friction 
of  the  tube,  and  the  adhesion  of  the  damp  paper  against  the 
action  of  gravity.  This  is  a  plain  statement  of  the  fact,  and 
the  explanation  should  be  intelligible,  without  the  mystifica- 
tion of  the  angles  of  a  pile  of  sand,  or  of  the  rolling  of  sand ; 
for  the  fact  has  no  reference  to  rolling,  nor  to  the  stability 
of  a  heap  of  sand  firmly  supported  at  its  base. 

The  reason  for  the  suspension  both  of  the  sand  and  of  the 
water  is  the  same.  It  is  not  the  pressure  of  the  atmosphere  ; 
for  this  pressure  is  neutralized  by  being  above  as  well  as 
below  the  suspended  matter.  The  force  of  a  falling  body  is 
gained  only  by  its  descent.  Relatively  to  the  containing 
vessel,  neither  the  sand  nor  water  has  descended.  It  has 
acquired  no  force,  and  it  is  not  attracted  downwards.  The 
glass,  raised  or  depressed  by  the  hand,  receives  from  it  the 
degree  of  force  for  its  different  levels.  The  water  and  the 
glass  are  as  one  mass  for  rotation,  the  force  being  equally 
diffused  through  them. 

The  reason  that  the  paper  makes  the  glass  and  its  con- 
tents as  one  mass  is  obvious.  It  arrests  the  beginning  of  the 

16 


182  OUTLINES    OF    A   SYSTEM   OF 

process  of  descent.  It  permits  no  particle  to  acquire  force 
of  descent.  It  could  not  withstand  an  attraction  of  gravity  ; 
but  it  prevents  any  fall  by  which  the  contents  of  the  glass 
can  acquire  force  for  the  downward  motion.  Take  away  the 
paper,  and  the  sand  or  water  will  issue,  the  surface  sink- 
ing as  stratum  by  stratum  the  descending  matter  makes 
room  for  the  upper  strata  to  descend.  Each  stratum  for 
itself  gains  force  of  descent  by  its-  descent ;  each  stratum 
quietly  waits  for  its  turn.  The  paper  prevents  the  com- 
mencement of  this  process,  and,  until  it  begins,  the  tube 
and  its  contents  rotate  at  any  level  as  one  mass,  with  the 
rotary  force  equally  diffused  through  it. 

We  have  thus  presented  water  remaining  suspended  with 
a  volume  of  air  above  it  of  the  same  elasticity  as  that  below 
it,  and  sand  supported  in  the  same  manner  with  the  weight 
of  the  whole  atmosphere  pressing  upon  it  above  as  well  as 
below.  We  pass  from  these  to  other  proofs  of  the  want  of 
attractive  power  in  the  earth. 

If  water  be  pressed  upon  by  a  piston,  as  in  a  common 
forcing-pump,  with  a  force  of  fifty  pounds,  this  pressure  will 
show  itself  in  the  strength  of  the  issuing  jet.  Now  take 
away  the  piston,  and  replace  it  with  what  under  the  law  of 
gravitation  would  be  an  exact  equivalent,  fifty  pounds  of 
water.  The  pressure  of  this  water,  if  it  were  attracted 
downward  by  the  earth,  would  be  equal  to  fifty  pounds  of 
external  force.  But  the  issuing  jet  is  not  increased  in 
nearly  the  same  ratio  as  when  pressure  was  applied  by  the 
piston.  The  fact  is,  that  the  added  water  has  no  pressure, 
and  the  increase  in  the  force  of  the  jet  by  its  addition,  re- 
sults only  from  the  lengthened  column  of  water,  which  gives 
increased  force  of  descent.  The  increased  force  of  the  jet 
bears  an  exact  mathematical  relation  to  the  increased  alti- 


MECHANICAL  PHILOSOPHY.  183 

tude.  Before  the  addition,  the  velocity  of  the  jet  at  the  ori- 
fice was  the  square  root  of  half  the  altitude  of  the  water. 
The  addition  of  the  fifty  pounds  gives  a  jet,  the  velocity  of 
which  is  the  square  root  of  half  the  new  altitude.  In  other 
words,  the  force  of  the  jet  is  the  force  of  rotation  unused  by 
the  water  which  has  descended  in  the  cylinder,  and  to  get 
this  measure,  the  mean  descent,  or  half  the  altitude  of  the 
descending  column  is  the  element  of  calculation.  The  water 
at  rest  is  not  attracted,  —  does  not  bear  upon  the  water 
below  it.  The  addition  of  the  fifty  pounds  alters  the  jet, 
only  by  increasing  the  elevation  from  which  the  water  falls. 

But  there  is  another  fact  relating  to  the  flow  of  water, 
which  is  beautifully  illustrative  of  the  views  we  present.  A 
jet  of  water,  issuing  from  the  orifice  of  a  containing  vessel, 
contracts  at  a  short  distance  from  the  orifice.  This  is 
technically  called  the  vena  contracta.  The  velocity  of  the 
issuing  jet  at  this  contracted  point  is  the  square  root  of  the 
whole  elevation  of  the  water,  while,  as  before  stated,  the 
velocity  of  the  jet  at  the  issuing  orifice  in  the  side  of  the 
vessel  is  only  the  square  root  of  half  the  elevation. 

We  believe  that  the  increased  velocity  of  issuing  water  at 
the  vena  contracta  has  never  been  satisfactorily  accounted 
for,  and  it  is  admitted  that  the  whole  subject  of  the  motion 
of  fluids  is  still  imperfectly  understood.  We  will  briefly 
sketch  the  history  of  speculation  on  this  subject,  taking  our 
account  chiefly  from  the  History  of  the  Inductive  Sciences, 
to  which  we  have  so  often  recurred  when  we  wished  for  a 
clear  statement  of  philosophical  opinion. 

Castelli  was  the  first  to  assert  that  the  velocity  of  efflux 
depended  on  the  depth  of  the  orifice  below  the  surface. 
Torricelli  also  stated  in  1643,  as  the  result  of  his  experi- 
ments, that  the  fluid  would  spout  nearly  to  the  height  of  the 


184  OUTLINES    OF   A    SYSTEM    OF 

surface,  and 'inferred  that  the  full  velocity  is  that  which  a 
body  would  have  in  falling  through  the  depth,  and  that  the 
velocity  is  consequently  proportional  to  the  depth. 

Newton,  in  his  Principia,  treated  the  subject  theoretically, 
that  is,  according  to  the  theory  of  gravitation  ;  but  "  La 
Grange  says  that  this  is  the  least  satisfactory  portion  of  that 
great  work."  Newton  made  experiments  different  from 
those  of  Torricelli ;  he  measured  the  quantity  instead  of 
the  velocity  of  the  flow.  The  velocity  inferred  from  the 
quantity  is  only  that  due  to  half  the  depth  of  the  water. 

Newton  explained  the  difference  by  observing  the  con- 
traction which  the  jet  of  water  undergoes  just  after  it  leaves 
the  orifice.  At  the  orifice  the  velocity  is  that  due  to  half 
the  height,  at  the  vena  contracta  it  is  that  due  to  the  whole 
height.  The  former  velocity  regulates  the  quantity  of  the 
discharge ;  the  latter,  the  force  of  the  jet. 

"  In  the  second  edition  of  the  Principia,  Newton  attacked 
the  problem  in  a  manner  altogether  different  from  his  former 
one.  He  there  assumes  that  where  a  round  vessel  contain- 
ing fluid  has  an  orifice  at  its  bottom,  the  descending  fluid 
may  be  conceived  to  be  a  conoidal  mass,  which  has  its  base 
at  the  surface  of  the  fluid,  and  its  narrow  end  at  the  orifice. 
This  portion  of  the  fluid  he  calls  the  cataract,  and  supposes 
that  while  this  part  descends,  the  surrounding  parts  remain 
immovable,  as  if  they  were  frozen  ;  in  this  way  he  finds  a 
result  agreeing  with  Torricelli' s  experiments  on  the  velocity 
of  efflux." 

"  We  must  allow  that  the  assumptions  by  which  this  result 
is  obtained,"  continues  Whewell,  "  are  somewhat  arbitrary ; 
and  those  which  Newton  introduces  in  attempting  to  connect 
the  problem  of  issuing  fluids  with  that  of  the  resistance  of  a 
body  moving  in  a  fluid  are  no  less  so.  Even  up  to  this 


MECHANICAL    PHILOSOPHY.  185 

time  mathematicians  have  not  been  able  to  reduce  problems 
concerning  the  motion  of  fluids  to  exact  calculation,  without 

introducing  some  steps  of  this  arbitrary  kind Hence 

the  science  of  the  motion  of  fluids,  unlike  all  the  other 
primary  departments  of  mechanics,  is  a  subject  on  which 
we  still  need  experiments  to  point  out  the  fundamental 
principles." 

We  would  ask  the  question,  —  may  it  not  be  found  that 
the  theories  connected  with  this  subject  require  an  examin- 
ation ?  The  facts  will  not  change  their  character  ;  the  jet 
of  water  will  ever  continue  to  bear  the  same  relation  to  the 
depth  of  the  column  as  in  the  days  of  Torricelli  and  Newton. 
The  quantity  of  water  flowing  out,  as  also  its  velocity  at  the 
orifice,  will  be  that  due  to  a  fall  from  one  half  the  height  of 
the  column  ;  its  velocity  at  the  vena  contracta,  and  the 
height  of  its  rise,  will  retain  their  relation  to  the  whole 
depth  of  the  column,  —  that  is,  at  the  orifice  the  velocity 
will  ever  be  the  square  root  of  the  half  altitude,  at  the  vena 
contracta,  the  square  root  of  the  entire  altitude. 

If  water  in  the  containing  vessel  were  the  subject  of  ter- 
restrial attraction,  the  force  of  the  jet  at  the  issuing  orifice 
would  be  determined  by  the  whole  weight  of  the  water.  As 
we  have  seen,  this  is  not  the  case.  Or  if  the  attraction 
acted  only  on  a  column  of  the  same  area  as  the  opening,  the 
force  of  the  jet  would  be  determined  by  the  whole  height  of 
the  column.  But,  as  we  have  before  said,  it  is  found  on 
experiment,  that  the  force  of  the  jet  at  the  orifice  and  the 
quantity  of  water  issuing,  is  that  which  is  due  to  one  half  the 
height  only.  On  our  principles,  the  force  of  the  jet,  being 
the  force  freed  by  descent,  could  be  related  only  to  one  half 
the  height ;  for  the  water  at  the  orifice  would  have  no  force 
of  descent  within  the  vessel,  while  the  water  at  the  surface 

16* 


186  OUTLINES    OF   A   SYSTEM   OF 

would  have  the  force  due  to  the  whole  distance  from  the  top 
to  the  aperture.  Of  course,  the  force  of  the  jet  would  be 
the  mean  force  of  the  column,  or  the  force  of  the  descent 
from  one  half  the  height.  This  appears  almost  perfect  proof 
that  it  is  force  from  descent,  and  not  an  attractive  force, 
which  gives  the  velocity  of  the  jet,  and  determines  the 
quantity  of  issuing  water.  If  gravitation  brought  down  the 
water,  the  whole  of  the  column  being  equally  attracted,  the 
force  of  the  jet  would  be  that  due  to  the  whole  height. 

As  the  force  of  the  jet,  therefore,  is  determined,  not  by 
the  quantity,  but  by  the  height  of  the  water  in  the  contain- 
ing vessel,  it  is  force  of  descent  only  which  governs  the 
intensity  of  the  flow.  There  can  be  no  difference  of  opinion 
thus  far.  Action  on  the  jet  is  confined  to  the  water  which  is 
in  motion.  In  fact,  the  impelling  power  is  usually  stated  to 
be  the  force  of  descent  induced  by  the  action  of  gravitation. 

But  this  force  of  descent  does  not  account  for  the  in- 
creased velocity  at  the  vena  contracta.  It  is  in  its  full 
intensity  at  the  moment  the  water  issues  from  the  orifice. 
All  the  power  produced  by  the  change  of  level  has  accumu- 
lated at  the  aperture,  and  after  the  water  has  issued  it  can 
receive  no  farther  increment  of  force  from  descent  within. 
Its  increase  of  velocity  after  it  has  left  the  vessel,  is  not 
therefore  from  the  force  of  descent.  Nor  is  the  motion  ac- 
celerated because  the  jet  is  contracted ;  as  the  quantity  of 
water  remains  the  same,  the  size  of  the  stream  depends  on 
the  velocity  of  its  passage.  The  contraction  is  occasioned 
by  the  more  rapid  flow  of  the  particles  of  water  ;  it  does 
not  cause  the  rapidity.  The  jet  occupies  less  space  because 
it  is  accelerated  ;  if  it  were  retarded,  it  would  increase  in 
circumference.  Most  unquestionably,  therefore,  the  water 
after  leaving  the  vessel,  after  its  possession  of  the  full  im- 


MECHANICAL   PHILOSOPHY.  1ST 

pulse  from  the  fall  within,  is  acted  upon  by  a  new  impelling 
power.  The  jet  is  doubled  in  velocity,  and  by  a  cause 
which  commences  its  action  after  the  issue  of  the  water. 
The  increase  of  velocity  at  the  vena  contracta  cannot  be 
caused  by  the  force  of  descent,  whether  this  force  of  de- 
scent comes  from  gravitation,  or  from  change  of  the  level  of 
rotation. 

But  the  increase  is  measured  by  the  depth  of  the  water 
from  which  the  jet  proceeds.  There  is  then  a  difference  in 
the  state  or  condition  of  water  according  to  its  depth.  This 
difference  is  in  the  degree  of  molecular  action.  As  we  have 
before  observed,  we  believe  that  the  force  of  rotation  de- 
creases from  the  surface  of  a  fluid  downward,  and  that  mole- 
cular force  increases  proportionally  in  the  same  direction,  — 
that  the  one  is  the  complement  of  the  other,  giving  to  the 
whole  volume  of  the  fluid  an  equal  diffusion  of  force.  The 
proofs  of  this  theory  seem  to  multiply  as  we  proceed.  And 
the  increase  of  the  velocity  of  the  jet  at  the  vena  contracta, 
not  only  shows  the  existence  of  this  molecular  force,  but 
gives  us  the  measure  of  its  intensity,  and  its  intensity  thus 
determined  presents  it  as  the  counterpart  of  the  force  gained 
by  descent. 

At  the  orifice  we  have  a  force  of  flow  which  is  due  only 
to  the  mean  descent  of  the  column  of  water  ;  at  the  vena 
contracta  we  have  an  additional  force  exactly  equivalent  to 
it,  so  that  at  this  point  the  force  is  equal  to  that  which  would 
be  disengaged  by  descent  from  the  whole  height  of  the 
column.  The  two  forces  are  therefore  the  exact  counter- 
parts of  each  other.  If  the  stratum  of  water  nearest  the 
orifice  has  no  force  of  descent,  it  is  compensated  by  a 
greater  molecular  force  ;  if  the  stratum  at  the  upper  surface 
has  less  molecular  energy,  it  is  compensated  by  its  greater 


188  OUTLINES   OF   A   SYSTEM   OF 

rotary  force. %  The  velocity  of  the  jet  at  the  orifice  is  the 
result  of  only  one  force  ;  at  the  vena  contracta  it  is  that  of 
the  sum  of  the  two  forces.  At  the  orifice  there  is  only  the 
force  of  descent ;  at  the  vena  contracta  the  force  of  the  mo- 
lecular action  is  added  to  it.  The  change  of  level  throws 
the  force  of  descent  into  action  on  the  jet ;  the  escape  from 
the  depth  changes  the  molecular  force  of  that  depth  into 
progressive  motion  at  a  short  distance  from  the  orifice. 

It  is  also  found  that  more  water  discharges  itself  from  a 
reservoir  through  a  short  pipe,  than  through  a  naked  aper- 
ture of  the  same  diameter  as  the  pipe.  This  fact  has  been 
explained  by  the  supposition,  that  "  the  issuing  particles 
corning  from  all  sides  to  escape,  cross  and  impede  each 
other  in  rushing  through  a  simple  opening,  as  is  proved  by 
the  narrow  neck  which  the  jet  exhibits  a  little  beyond  the 
opening ;  but  in  a  tube  this  narrowing  of  the  jet  cannot 
happen  without  leaving  a  vacuum  around  the  part,  and  the 
pressure  of  the  atmosphere  resisting  the  vacuum  causes  a 
quicker  flow."  Surely  the  results  of  atmospheric  pressure 
induced  by  the  attraction  of  gravitation  are  many  and  won- 
derful !  Here  we  have  an  increased  efflux  of  water  by  the 
pressure  of  air  against  it ! 

The  contraction,  as  we  have  observed,  is  caused  by  the 
increased  velocity  of  the  jet ;  for  of  course  from  the  more 
rapid  motion  of  the  water,  there  is  less  of  it  at  any  one  mo- 
ment at  any  one  point  of  its  path.  The  effect  of  the  short 
tube  is  to  prevent  the  full  contraction,  by  the  adhesion  of  the 
water  to  its  interior  surface  ;  but,  as  this  adhesion  does  not 
overcome  all  the  gain  of  velocity  by  the  transfer  of  molecu- 
lar into  progressive  motion,  the  force,  instead  of  acting  at  a 
distance  from  the  aperture,  diffuses  itself  and  makes  an 
average  velocity  of  all  the  water  in  the  pipe.  By  friction 


MECHANICAL  PHILOSOPHY.  189 

the  additional  velocity  is  thrown  back  to  the  aperture, 
increasing  the  speed  of  the  fluid  through  it.  To  obtain  the 
greatest  possible  increase  of  flow,  the  tube  should  first  nar- 
row to  the  point  where  the  vena  contracta  forms  in  the 
natural  jet ;  this  gives  time  for  the  transfer  of  atomic  into 
progressive  motion ;  then  it  should  widen  from  this  point  so 
that  the  water  may  spread  itself  with  the  increased  flow.  It 
will  be  seen  that  the  effect  of  this  appliance,  —  technically 
the  conical  ajutage,  —  is  to  make  the  velocity  of  the  vena 
contracta  the  same  with  that  at  the  point  of  efflux,  —  the 
velocity  at  the  opening.  Increased  velocity  at  the  aperture 
emits  a  greater  quantity  at  any  one  time  than  would  pass 
with  a  less  velocity.  The  greater  the  efflux,  the  greater  the 
force  of  descent,  and  the  greater  the  addition  to  the  flow 
by  the  action  of  the  molecular  force. 

It  appears  to  us  a  clear  explanation  of  the  effect  of 
conical  ajutages,  to  consider  them  as  the  means  by  which 
the  force  that  without  them  would  act  only  away  from  the 
opening,  increasing  the  velocity  at  a  distance  from  it,  is 
made  to  act  at  the  opening  where  the  greater  velocity  passes 
through  the  aperture  a  greater  quantity  of  water  in  a  given 
time.  By  the  retardation  of  the  flow  of  the  water  by  the 
friction  of  a  pipe,  the  force  of  the  flow  is  not  annihilated. 
It  is  still  in  being,  and  if  its  onward  action  be  impeded,  it  is 
thrown  back  toward  the  opening,  giving  passage  to  more 
water  from  the  reservoir.  And  with  more  water  comes  its 
own  force  of  propulsion,  and  of  reflex  influence.  So  the 
gain  in  the  flow  is  limited  only  by  the  quantity  of  molecular 
action  which  the  depth  of  the  reservoir  can  supply,  and 
that  is  limited  to  what  would  be  the  force  of  descent  if  all 
the  issuing  water  fell  from  the  upper  surface  of  the  reservoir. 

By  the  theory  of  gravitation  the  efflux  of  water  from  the 


190  OUTLINES    OF  A   SYSTEM   OF 

opening  in  the  reservoir  is  represented  as  the  effect  of  terres- 
trial attraction,  and  yet  there  is  an  admitted  impossibility  of 
giving  by  this  theory  any  thing  which  approximates  to  a 
clear  explanation.  Why,  if  the  water  in  the  reservoir  is 
attracted,  and  the  result  of  this  attraction  is  an  equal  press- 
ure in  every  direction,  does  not  the  jet  respond  to  this 
pressure  when  it  answers  at  once  to  the  presence  of  any 
external  force  so  applied  as  to  bear  upon  the  particles  of 
the  water  in  any  direction  ?  If  there  can  be  clear  proof  of 
any  position  whatever,  there  is  this  clear  proof  that  gravita- 
tion does  not  in  the  least  degree  press  together  the  particles 
of  a  fluid. 

Why  again  is  the  issuing  jet  imputed  to  the  force  of 
descent  induced  by  gravitation,  when  it  is  so  palpably  evi- 
dent that  a  part  of  the  velocity  of  the  jet  comes  after  the 
descent  has  exerted  its  full  influence,  and  when  the  quantity 
of  water  discharged  is  increased  by  an  appliance  which  can- 
not possibly  be  supposed  to  have  the  least  effect  in  increas- 
ing the  force  of  descent  ?  And  why  impute  the  whole  force 
of  the  jet  to  a  cause,  which  if  it  act  at  all,  can  produce  only 
a  moiety  of  this  force  ? 

On  the  other  hand,  have  not  we  a  theory  which  gives  a 
distinct  idea  of  the  cause  of  these  phenomena  ?  One  moiety 
of  the  force  of  the  discharge  comes  from  the  change  of 
level,  —  the  unused  rotary  force  resolved  into  other  mo- 
tion ;  the  other  moiety,  from  the  resolution  of  molecular 
force  into  progressive  motion.  United  they  are  sufficient 
again  to  raise  the  water,  as  it  flows  into  another  recep- 
tacle, to  the  height  from  which  it  fell,  —  the  spare  force  of 
rotation  being  again  transferred  to  rotation,  the  molecular 
force  being  again  translated  into  the  atomic  action  due  to  a 
depth  equal  to  that  from  which  the  water  issued. 


MECHANICAL  PHILOSOPHY.  191 

Practical  men  recognize  these  principles  in  the  construc- 
tion of  their  machinery.  The  molecular  force  distributed  as 
the  counterpart  of  the  rotary,  increases  regularly  from  the 
lower  surface  upward.  As  a  cone,  with  its  base  at  the 
lower  stratum,  and  its  apex  at  the  upper,  must  be  divided 
at  one  third  of  its  altitude,  to  leave  equal  quantities  in  each 
portion,  so  the  molecular  force  is  divided  ;  the  centre  or 
equilibrium  of  power  in  every  column,  whatever  its  height, 
is  at  one  third  of  the  altitude  from  the  lower  surface.  To 
support  a  sluice,  or  flood-gate,  or  embankment,  the  support 
is  made  to  press  at  one  third  of  the  height. 

A  practical  millwright,  on  being  asked  if  it  made  any 
difference  how  the  water  was  let  on  to  his  wheel,  replied, 
"  On  the  overshot  or  vertical  wheel  it  does  not  make  any 
difference ;  in  whatever  way  the  water  runs  out,  I  get  its 
whole  weight  as  it  strikes  the  wheel ;  but  I  confine  that 
which  issues  from  below  on  the  central,  or  horizontal  wheel, 
so  that  it  shall  not  spread  until  it  strikes  the  wheel,  for 
thereby  I  get  the  4  spring'  of  the  water."  "  But  you  know 
that  water  is  incompressible  ;  how  can  it  have  a  spring  ?  " 
"  It  may  be  so,"  replied  the  mechanic,  "  but  I  know  that 
water  issuing  from  below  has  a  spring  to  it." 

We  are  far  from  having  exhausted  this  branch  of  the  sub- 
ject ;  but,  as  it  has  already  occupied  an  undue  share  per- 
haps of  our  space,  we  pass  to  a  cursory  consideration  of  the 
ebullition  of  water,  and  of  the  action  of  steam. 

By  recognizing  the  action  of  molecular  force,  we  are  ena- 
bled to  comprehend  a  peculiarity  of  water  in  its  conduction 
of  heat.  It  is  almost  impossible  to  heat  water  from  the  sur- 
face downwards.  Heat  can  hardly  be  propagated  in  this 
direction  through  the  fluid.  If  it  is  applied  at  the  surface, 
the  upper  stratum  only  receives  the  force,  and  is  converted 


192  OUTLINES   OF  A   SYSTEM   OF 

by  it  into  vapor,  which  passes  off.  But  when  the  lower 
stratum  receives  the  force,  it  distributes  it  normally  through 
the  volume,  the  molecular  action  being  gradually  increased 
until  ebullition,  that  is,  vaporization  from  every  stratum, 
ensues.  The  lower  strata,  not  the  surface,  regulate  mole- 
cular action ;  without  the  application  of  artificial  heat,  it  is 
additional  depth  which  increases  its  intensity.  The  force 
thus  acting  in  the  lower  stratum  determines  that  of  all  the 
succeeding  strata ;  therefore,  it  is  only  by  artificially  increas- 
ing the  force  of  the  lower  surface,  that  this  increase  can  be 
extended  through  the  whole  volume.  Our  views  receive 
confirmation  from  the  fact,  that  water  artificially  heated  is 
always  hottest  at  the  bottom  of  the  vessel ;  in  very  deep 
boilers,  the  liquid  is  much  more  heated  than  it  can  be  in 
smaller  vessels. 

When  there  is  no  application  of  artificial  heat,  the  mole- 
cular force  present  in  water  depends  upon  the  degree  of 
rotary  force.  Therefore  water  boils  with  less  added  heat, 
according  to  the  degree  of  its  elevation.  At  a  great  alti- 
tude, as  water  is  already  in  possession  of  a  high  degree  of 
rotary  force,  it  does  not  require  so  much  additional  force 
to  bring  the  molecular  action  to  that  degree  of  intensity 
which  changes  it  into  steam.  At  the  summit  of  Mont  Blanc 
water  boils  at  180°  of  Fahrenheit,  —  32°  less  than  at  the 
level  of  the  ocean.  By  the  changes  of  rotary  force  upon 
the  surface  of  the  earth,  vaporization  from  water,  and  even 
from  snow  and  ice,  is  induced  and  suspended.  This  vapor 
is  not  expansive,  having  space  for  its  range  of  molecular 
motion. 

Steam  has,  of  course,  a  most  intense  molecular  action, 
and,  when  generated  under  confinement,  it  has  not  sufficient 
range  of  space  for  its  normal  motion.  Hence  its  expansive 
power. 


MECHANICAL  PHILOSOPHY.  193 

Ebullition  does  not,  in  the  least  degree,  depend  upon 
atmospheric  pressure.  Air,  in  its  normal  condition,  does 
not  act  upon  water.  But  if  air  be  artificially  condensed 
over  water,  as  in  a  steam-boiler  for  instance,  by  the  rising 
of  steam  in  it,  there  is  then  a  pressure  of  the  air  upon  the 
water,  and  there  is  less  space  for  the  water  to  diffuse  itself. 
When  closely  confined,  without  space  for  enlargement,  water 
can  be  heated  red  hot  without  passing  into  vapor.  The  de- 
gree of  the  confinement  therefore  measures  the  resistance  to 
the  change  of  water  into  steam.  In  practice,  the  resistance 
is  the  impelling  force  which  moves  the  piston.  Hence  the 
importance  of  confining  steam  in  as  small  a  compass  as  pos- 
sible, and  not  allowing  it  to  expand  except  in  that  direction 
in  which,  by  the  act  of  expansion,  it  can  move  the  machin- 
ery. The  force  of  steam  is  its  demand  for  greater  space  for 
its  molecular  action.  That  attained,  it  is  no  longer  the 
source  of  motive  power.  It  cannot  be  recompressed  with- 
out the  use  of  as  much  force  as  it  would  give  out  by  its  re- 
enlargement.  Great  expense  is  often  incurred  by  the  want 
of  a  clear  understanding  of  this  principle.  In  an  artificial 
vacuum  on  the  other  hand,  there  is  greater  space  for  the 
molecular  action  of  the  remnant  of  air  than  is  normal  to  it, 
and  if  water  is  placed  in  the  vacuum,  the  equilibrium  is 
restored  by  its  vaporization.  So  great  at  times  is  this  va- 
porization, that  there  is  not  force  enough  left  in  the  remain- 
ing water  to  preserve  its  fluidity,  and  it  becomes  frozen. 

The  increased  capacity  of  water  for  heat  in  proportion  to 
its  depth,  to  which  we  have  alluded,  is  of  course  attributed 
to  the  pressure  of  the  upper  water,  which  is  supposed  to  pre- 
vent the  escape  by  vaporization  of  the  heat  from  the  pressed 
strata.  Can  this  be  a  well-founded  opinion,  since  gravitation 
neither  directly  nor  by  pressure  can  have  power  over  heat  ? 

17 


194  OUTLINES   OP   A    SYSTEM   OF 

Nor  is  it  necessary  that  there  should  be  vaporization  to  pro- 
duce an  equal  diffusion  of  heat  throughout  any  one  volume 
of  fluid.  The  lower  strata  retain  the  augmented  heat  on  the 
same  principle  on  which  they  retain  the  molecular  force. 
The  additional  force  of  heat  is  diffused  in  a  decreasing  ratio 
from  the  bottom  to  the  surface  of  the  fluid. 

We  will  advert  to  another  of  the  supposed  results  of  the 
gravitating  power.  It  is  believed  that,  if  the  pressure  of  the 
atmosphere  were  withdrawn,  many  substances  now  solid 
would  become  fluid,  and  many  fluids,  aeriform ;  that  water 
with  a  slight  increase  of  heat,  would  change  itself  into  vapor, 
were  it  not  for  the  weight  of  the  air  upon  it ;  and  that  in 
fact  it  is  by  the  gravitation  of  the  atmosphere  that  even  the 
ocean  remains  in  its  place. 

There  is  one  striking  peculiarity  in  the  philosophy  of 
gravitation.  According  to  it  no  matter  in  the  universe 
moves  or  keeps  in  place  without  the  control  of  other  mat- 
ter. Every  particle  is  endowed  with  energy  to  give  motion 
to  other  particles  ;  but  it  has  none  for  its  own  motion.  Thus 
nothing  is  able  to  take  its  own  position,  to  be  what  and 
where  it  is,  from  itself,  from  its  inherent  fitness  ;  but  every 
mass  is  perfectly  competent  to  press  into  place  adjacent 
masses  or  volumes,  and  these  in  their  turn  to  press  it  into 
proper  position.  And  this  is  deemed  true,  not  of  adjacent 
masses  only,  but  of  masses  millions  of  miles  distant,  and  that 
against  the  action  of  the  force  with  which  they  were  endowed 
at  their  creation.  Thus  one  sphere  determines  the  orbit  of 
another,  itself  being  guided  in  its  turn  by  an  emanation  from 
some  other  centre  of  influence,  and  hence  there  is  order  and 
permanence  in  the  system  of  worlds. 

It  may  be  said  that  this  feature  of  the  theory  of  universal 
gravitation  is  not  objectionable,  because  the  order  of  nature 


MECHANICAL    PHILOSOPHY.  195 

may  be  as  firmly  preserved  by  the  indirect  action  of  matter, 
as  by  the  immediate  power  of  every  atom  to  move  in  its 
destined  path,  and  to  preserve  its  own  proper  position. 

It  is  true  that,  whatever  be  the  character  of  our  philoso- 
phy, it  cannot  change  the  perfect  and  the  permanent.  The 
worlds  will  roll  on  in  their  orbits  and  fulfil  their  appointed 
rounds,  whether  we  believe  them  endowed  directly  with 
power  from  the  hands  of  their  Maker,  or  think  of  them  as 
under  the  control  of  other  parts  of  the  creation.  But  theo- 
ries have  value  in  proportion  to  their  effect  in  strengthening 
our  conceptions  of  the  wisdom  and  power  by  which  the  uni- 
verse is  continually  upheld,  —  in  leading  our  minds  upward 
to  the  Great  First  Cause,  instead  of  allowing  them  to  rest 
in  the  finite  and  the  created.  The  first  work  of  philosophy 
is  to  divide  the  incomprehensible  from  that  which  can  be 
clearly  apprehended,  that  the  one  may  be  made  the  subject 
of  investigation,  the  other  be  used  only  to  lift  our  thoughts 
to  the  wisdom  and  power  of  God.  Would  that  every  theory 
were  destroyed  which  furnished  to  the  mind  even  the 
appearance  of  a  resting  place  between  the  Creator  and  his 
works. 

By  referring  the  motions  and  positions  of  matter  to  mu- 
tual action,  we  receive  no  clear  idea,  we  take  no  step  in 
advance.  We  still  rest  on  the  power  of  matter  to  induce 
motion,  —  to  do  that  indirectly  which  we  are  not  willing  to 
admit  that  it  can  do  directly.  To  us.  and  perhaps  to  other 
minds,  the  theory  that  every  part  of  the  universe,  each 
atom,  volume,  mass,  is  guided  by  force  present  with  it, 
unaided  by  the  influence  or  mediation  of  other  matter,  has 
a  value  because  it  strengthens  our  conviction  of  the  perfect- 
ness  of  the  creation,  —  because  it  leads  us  to  recognize  in  all 
the  changes  of  matter  the  Guiding  Hand  which  sustains, 


196  OUTLINES    OF   A   SYSTEM    OF 

controls,  arid  directs  it.  It  presents  to  us  every  element  as 
in  its  place  by  reason  of  its  construction,  —  as  discharging 
its  functions  by  the  inherent  fitness  of  its  constitution,  —  by 
a  fitness  not  borrowed  from  other  matter,  but  imparted 
to  it  at  once  from  the  Source  of  all  perfection.  It  brings 
before  us  general  order  from  the  perfectness  of  each  part. 
We  recognize  in  harmony  of  action,  as  it  were  a  sympathetic 
movement,  not  a  compelled  conformity, — not  the  equilibrium 
of  well  balanced  opposition.  We  think  that  every  part  of 
the  structure  of  the  worlds  stands  firm  because  it  was  so 
created,  —  not  because  it  is  supported  by  the  insecure 
balance  of  opposite  leanings  from  the  true  direction. 

The  ocean  appears  to  us  as  a  most  beautiful  instance  of  an 
element,  perfect  in  its  adaptation  to  its  place,  —  in  its  fitness 
to  fulfil  all  the  purposes  of  its  creation.  It  is  not  held  to  its 
bed  by  the  pressure  of  the  atmosphere  upon  it,  but  works  as 
if  in  sympathy  with  it ;  it  is  not  chained  down  to  its  depths, 
but,  as  if  exultingly,  it  lavishes  its  force  to  aid  in  the 
harmony  of  the  world's  movement.  It  seems  to  rejoice  that 
it  is,  and  that  it  acts.*  Though  by  its  constitution  so 

*  Since  writing  the  above  we  have  met  with  the  following  beautiful  pas- 
sage, in  an  article  from  Kev.  A.  P.  Peabody,  in  a  recent  number  of  the 
North  American  Review,  which  has  given  us  so  much  pleasure  that  we 
cannot  forbear  transcribing  it :  "  We  are  reminded  in  this  connection  of 
an  apostrophe  to  the  sea,  in  the  Prometheus  of  ^Eschylus,  which,  in  four 
words  conveys  much  more  to  our  apprehension,  and  reflects  far  more  fully 
our  own  unutterable  emotion  in  the  frequent  survey  of  ocean  scenery,  than 
could  be  done  by  volumes  of  the  most  glowing,  eloquent,  passionate  de- 
scription. Whenever  we  look  iipon  the  ocean,  whether  from  deck,  beach, 
or  crag,  by  sunshine,  moonlight,  or  its  own  phosphorescent  glow,  we  find 
ourselves  absolutely  haunted,  sprighted,  by  these  words,  as  they  pulse  upon 
the  inward  ear  in  unison  with  the  rhythm  of  the  waves.  The  passage  to 
which  we  refer  is  that  where  Prometheus,  in  calling  on  all  nature  to  witness 
his  cruel  wrongs  at  the  hand  of  Jupiter,  addresses  the  sea  as 


MECHANICAL    PHILOSOPHY.  197 

nearly  poised  between  the  solid  and  the  aeriform  state,  it  is 
in  no  peril,  from  the  vicissitudes  of  temperature,  of  losing 
its  form  and  condition  by  passing  into  either  extreme.  It 
is  not  in  dangerous  equilibrium.  Its  own  construction  pro- 
tects it  on  either  hand,  and  its  inherent  safeguard  strengthens 
as  the  volume  of  water  deepens.  A  mere  surface  stratum 
only  can  harden  into  ice,  or  pass  away  in  vapor.  The  heat 
of  the  tropical  sun  cannot  penetrate  it ;  under  its  direct 
rays  are  thousands  of  miles  of  ocean  surface  with  a  perma- 
nent and  uniform  temperature,  and  water  drawn  from  the 
depths,  even  under  the  equator,  has  the  icy  coldness  of  the 
water  of  the  polar  seas.  The  unused  force  of  rotation  and 
revolution,  laid  up  as  in  a  storehouse  of  strength,  is  securely 
held  in  the  molecular  action,  so  that  by  degrees  only  it 
ascends  to  the  surface  and  passes  off  in  vapor ;  or  by  conduc- 
tion to  the  air  as  heat  mellows  the  rigor  of  winter  on  the  sea- 
girt shore.  So  securely  is  this  force  held,  that  from  the 
equator  to  48°  north  and  south  of  it,  the  mean  tempera- 
ture is  but  a  few  degrees  above  that  of  the  air.  Yet  we 
know  that  it  has  force  proportional  to  its  depth ;  for  the 
thermometer  will  determine  the  presence  of  shoal  places  as 
well  as  the  sounding  lead  ;  and  the  cold  water  of  shallows 
condenses  the  vapor  of  the  air  over  them,  so  that  often, 
clouds,  sharp  and  well  defined,  map  out  accurately  the  form 

xvnuTiar  tert'tQi&uov  ytlaaua.  This  cannot  be  transfused  without  damage 
into  another  language. 

"Tis  odor  fled, 
As  soon  as  shed.' 

We  know  not  how  to  convey  in  current  English  the  multiform  unity  indi- 
cated by  the  original.  '  The  innumerable  laugh  of  the  sea-ivavesj  is  literal, 
but  awkward.  '  The  many  tivinkling  smile  of  ocean,'  (which  we  copy  from  a 
Lexicon,)  is  preferable  on  the  score  of  euphony,  but  less  adequate  to  the 
sense." 

17* 


198  OUTLINES    OF   A   SYSTEM   OF 

of  the  banks  beneath.  The  force  regularly  set  free  from 
the  ocean  preserves  the  equilibrium  of  the  atmosphere  over 
it,  so  that,  far  away  from  land,  there  are  not  the  frequent 
and  sudden  irregularities,  the  disturbances  from  conflicting 
winds,  which  occur  where  islands  break  up  the  continuity 
and  interrupt  the  regular  transmission  of  force. 

We  referred  in  a  former  chapter  to  the  ocean  as  being  a 
storehouse  of  force,  —  as  the  conducting  element  by  which 
the  unused  energies  of  rotation  and  revolution  are  redis- 
tributed. How  perfectly  adapted  for  this  purpose  are  the 
oceans  from  their  position  !  There  is  no  unbroken  circuit  of 
land  passing  round  the  earth  as  a  barrier  against  the  passage 
of  force  from  one  hemisphere  to  the  other.  There  are  few 
broad  surfaces  of  land  which  are  not  broken  up  by  intruding 
bays  or  inland  seas.  North  and  south  around  the  poles,  the 
Arctic  and  Antarctic  Oceans  open  free  communion  ;  for 
there  are  changes  about  the  magnetic  poles  demanding  trans- 
fers of  force  for  the  restoration  of  an  equilibrium.  And 
from  the  equator  to  the  poles  on  either  hand,  between 
which  the  greatest  difference  of  temperature  and  of  rota- 
tive force  exists,  by  the  broad  sheets  of  the  Atlantic  and 
Pacific  stretching  from  pole  to  pole,  is  the  communication 
kept  fully  open. 

We  now  pass  to  the  consideration  of  the  atmosphere.  If 
a  weight  bearing  upon  the  surface  of  the  ocean  were  neces- 
sary to  prevent  it  from  passing  off  by  vaporization,  the 
atmosphere,  as  it  is  constituted,  could  not  supply  this  press- 
ure. As  the  air  exists  in  its  normal  state,  it  is  without 
power  to  bear  with  force  against  an  adjoining  volume  of 
other  matter.  Air  can  press  by  its  elastic  power  alone, 


MECHANICAL    PHILOSOPHY.  199 

and  it  manifests  elasticity  only  when  there  is  not  sufficient 
space  for  its  molecular  action.  Its  elasticity  becomes  appa- 
rent by  compression,  —  it  is  the  throwing  back  the  force 
which  disturbs  the  normal  position  of  its  particles.  Like 
steam,  air  must  have  its  molecular  action  artificially  re- 
pressed by  confinement  in  order  to  manifest  its  elastic  force. 
The  only  pressure  of  aeriform  bodies  is  from  want  of  space 
for  the  action  of  the  force  present  with  the  atoms. 

As  the  atmosphere  exists  in  its  natural  state,  its  molecu- 
lar force  is  determined,  as  in  the  case  of  the  denser  fluid, 
water,  by  its  degree  of  rotary  force.  Its  atomic  force 
therefore  increases  in  every  stratum,  from  the  highest  to 
the  lowest,  as  the  counterpart  of  its  progressive  force.  We 
cannot  see  a  current  of  heated  air  pass  upward  without 
noticing  in  its  vibrations  the  intensity  of  its  molecular  action, 
which,  as  it  ascends,  is  absorbed  in  rotary  motion  at  a 
higher  level.  This  atomic  force,  constituting  elasticity  when 
under  confinement,  when  unconfined  has  its  normal  space, 
—  has  all  the  room  that  it  needs  for  its  motion.  Of  course, 
it  cannot  bear  upon  or  press  any  matter  in  contact  with  it. 
We  might  as  well  look  for  motive  power  by  the  expansion 
of  the  free  vapor  rising  from  the  surface  of  the  ocean,  as  to 
seek  in  unconfined  air  for  the  power  of  pressure.  In  both 
cases  the  particles  have  freedom  and  space  for  motion  with- 
out impingement  upon  each  other,  or  upon  surrounding 
matter.  Nature  does  all  things  well.  There  is  no  tendency 
in  matter  to  escape  from  her  adjustments.  There  is  no 
crowding,  —  no  contest  for  space.  All  things  conform  one 
to  another.  Force,  matter,  space,  are  in  due  relation. 
There  may  be  an  occasional  oscillation,  —  for  a  time  a  lim- 
ited swerving  from  an  accustomed  relation,  but  how  soon 
the  storm  subsides  !  It  is 'not  a  struggle  for  mastery,  the 


200  OUTLINES   OF  A   SYSTEM   OF 

continued  battle  of  contending  forces,  which  gives  the  peace 
of  nature.  It  is,  as  we  have  said,  the  constituted  fitness  of 
all  things  for  their  assigned  place  and  office. 

Air  and  water  rest  in  contact  without  mutual  pressure 
because  they  are  in  place.  If  one  causes  motion  in  the 
other,  it  is  by  the  transfer  of  force.  When  air  is  artificially 
condensed  the  force  of  elasticity  manifests  itself,  and  then 
there  is  pressure  ;  but,  as  this  is  the  effect  of  the  unnatural 
condition,  it  does  not  outlast  the  confinement.  Set  free, 
the  condensed  air  rushes  instantly  into  the  more  rarefied, 
diffuses  itself  where  there  is  relatively  greater  space  for 
motion,  and  an  equilibrium  is  at  once  restored.  What  is 
true  of  a  smaller,  isolated  volume  of  air,  is  true  of  the  whole 
atmosphere.  The  law  of  nature  is  uniform  ;  the  same  force 
which  diffuses  a  confined  portion  when  it  is  set  free,  is  ever 
in  unobserved  action,  so  that  the  whole  element  is  in  equili- 
brium in  relation  to  its  own  particles,  and  in  its  relation  to 
other  matter  ;  the  law  of  its  nature  forbids  a  permanent  and 
continuous  pressure  upon  other  matter. 

That  air  is  elastic  in  proportion  to  its  density  has  been 
proved  by  the  most  accurate  experiments,  performed  by  a 
commission  of  the  French  Academy  of  Science.  To  state 
the  fact  in  other  words,  the  force  with  which  air  will  diffuse 
itself  is  in  proportion  to  its  density  -compared  with  that  of 
the  surrounding  air.  Elasticity,  therefore,  is  the  power  of 
diffusion,  by  which  the  pressure  ceases  to  be,  —  by  which  it 
is  annihilated  in  consequence  of  the  return  of  the  whole 
volume  to  its  normal  condition.  Thus,  the  elasticity  of  a 
bent  bow,  so  soon  as  it  is  straightened,  no  longer  manifests 
its  presence,  for  the  atoms  of  the  bow  have  returned  to  their 
normal  state  and  are  at  rest. 

What  view  of  this  subject  does  the  theory  of  gravitation 


MECHANICAL   PHILOSOPHY.  201 

present  ?  It  supposes  a  continued,  a  permanent  pressure  of 
the  particles  of  air,  stratum  on  stratum,  causing  differing 
degrees  of  density  in  every  layer,  the  pressure  decreasing 
from  the  surface  of  the  earth  upward  till  the  air  gradually 
fades  away  into  the  vacancy  of  space.  It  gives  to  air  a 
continued  struggle  for  space,  —  an  abiding  elasticity,  —  an 
elasticity  acting  in  every  direction,  bearing  upward  as  well 
as  downward.  It  presents  the  atmosphere  as  a  series  of 
springs,  increasing  in  the  power  of  reaction  from  above 
downward,  and  all  of  these  bent  springs  secured  at  one  end, 
only  with  nothing  to  resist  the  expansion  of  the  other  end, — 
the  elasticity  of  the  air  increasing  with  its  density,  its  dens- 
ity increasing  with  its  depth,  and  this  elasticity  acting  with 
equal  force  in  every  direction !  We  know  that  the  expan- 
sive power  of  the  air  throws  the  more  dense  portions  upward 
into  the  more  rarefied.  What  therefore  keeps  down  the 
atmosphere,  which,  according  to  theory,  presses  upward  as 
well  as  downward,  against  itself  and  all  other  matter,  with  a 
force  of  fifteen  pounds  to  the  inch  ? 

We  cannot  avoid  the  belief  that  the  views  which  we  have 
presented  accord  more  nearly  with  the  facts.  The  air  is 
neither  drawn  down  to  the  earth  by  attraction,  nor  repelled 
from  it  by  its  own  elasticity.  It  holds  its  place,  because  it 
is  so  constituted  as  to  retain  the  due  force  of  rotation  for  its 
level  of  rotation.  It  has  no  tendency  to  escape  into  the  re- 
gions of  space,  nor  to  crowd  into  the  bed  of  the  ocean.  It 
occupies  its  allotted  place  without  an  effort  to  expand  or  to 
contract  its  volume.  It  is  without  elasticity  when  uncom- 
pressed,—  without  weight  when  resting  at  one  level.  Its 
motion  is  from  the  reception  of  force,  —  its  permanency,  be- 
cause God  gave  to  it  the  atomic  and  elementary  construction 
which  fits  it  for  its  position,  and  for  its  office  in  the  economy 


202  OUTLINES   OF  A   SYSTEM   OF 

of  nature.  '  It  did  not  fit  itself  for  its  place  and  function,  nor 
is  it  guarded  and  restrained  by  other  matter  as  dead  and 
senseless  as  itself. 

That  gravitation  cannot  by  its  force  draw  down  the  atmo- 
sphere, so  that  its  density  shall  increase,  stratum  after  stra- 
tum, from  above  downward,  or  if  the  atmosphere  exists 
with  this  increasing  ratio  of  density,  that  it  is  not  the  action 
of  gravitation  which  retains  it  in  its  position,  is  distinctly 
proved  by  the  operation  of  the  air-pump  ;  for  the  compara- 
tively denser  air  of  the  receiver  invariably  rises,  against  the 
attraction  of  the  earth,  into  .the  rarer  medium  between  the 
valves.  Thus  against  gravitation  would  the  denser  air  near 
the  earth  rise  up  into  the  more  rarefied  strata  above,  till  an 
equilibrium  of  density  was  established.  "  We  know  not," 
says  Dr.  Arnott,  "  at  what  distance  the  gravity  of  the  par- 
ticles of  air  becomes  just  a  balance  to  their  repulsive  force, 
and  therefore  know  not  what  the  degree  of  rarity  is  at  the 
top  of  our  atmosphere,  but  we  see  that  it  must  be  exceed- 
ingly great  from  the  fact  that  the  air  left  in  the  receiver  of 
an  air-pump  has  still  spring  enough  to  lift  the  valve  of  the 
pump,  when  there  is  less  than  one  thousandth  of  the  original 
quantity  remaining.''  If  the  air  in  the  receiver  has 
"  spring "  enough  left  for  its  elevation,  though  so  vastly 
reduced  in  density,  why  is  not  the  spring  of  the  denser 
strata  of  the  atmosphere  a  sufficient  force  for  their  elevation 
into  the  more  rarefied  ? 

This  illustration  introduces  us  to  the  next  branch  of  our 
subject,  —  the  vacuum.  We  do  not  entertain  the  idea  that 
nature  abhors  a  void  place,  but  we  believe,  to  speak  meta- 
phorically, that  nature  abhors  and  resists  the  infraction  of 
her  laws,  one  of  which  is,  that  force  shall  be  equably 
diffused  according  to  altitude.  Force,  in  distributing  itself, 


MECHANICAL    PHILOSOPHY.  203 

will  carry  into  a  void  place  the  adjacent  matter,  so  that  in 
the  onward  current  of  rotation  there  shall  be  no  vacant 
space.  The  fall  or  rise  of  matter  from  the  stream  at  one 
level  into  the  stream  at  another,  is  but  the  interchange  of 
place  of  equal  volumes.  In  the  creation  of  a  vacuum, 
however,  there  is  a  change  without  the  equipoising  change, 
and  the  filling  of  a  vacuum,  whenever  it  takes  place,  is  the 
same  act  as  if  the  equipoise  had  been  preserved  when  the 
matter  was  first  removed.  Thus  vacua  are  filled,  let  the 
time  be  never  so  remote  from  their  formation,  whenever  the 
adjacent  matter  is  susceptible  of  the  change  of  form  neces- 
sary for  the  purpose,  and  filled  with  the  same  degree  of  force 
with  which  they  were  made  void.  Air,  extensible  without 
limit,  will  always  fill  a  vacuum,  as  will  water  and  other  fluids 
to  the  limit  of  their  extension ;  solids  will  be  forced  against  or 
into  it  to  the  degree  that  their  form  and  elasticity  will  permit. 
To  repeat  the  idea  ;  the  force  used  to  create  a  vacuum 
measures  the  force  with  which  it  is  filled.  For  instance,  if 
the  air  be  drawn  from  a  vessel,  the  force  which  will  cause 
other  air  to  rush  into  it,  is  equal  in  intensity  to  that  which 
displaced  the  air.  The  force  required  to  fill  a  vacuum  is 
not  determined  by  the  gravity  of  the  external  air,  for  that 
must  be  invariable.  Matter  lifted  up  does  not  increase  in 
weight  according  to  the  distance  to  which  it  is  lifted,  nor  has 
it  more  weight  of  air  over  it  when  elevated  one  foot  than  when 
raised  six  inches ;  yet  the  higher  a  piston  is  lifted  in  making  a 
.vacuum,  the  more  force  is  required,  and  with  the  more  force 
does  it  return.  Suppose  a  tube  in  which,  by  the  elevation 
of  a  piston,  a  theoretically  perfect  vacuum  is  formed.  The 
air  is  believed  to  press  upon  every  inch  of  the  surface  of  the 
tube  and  piston  with  a  force  of  fifteen  pounds.  Raise  the 
piston  one  foot,  the  air  bears  on  its  outside  surface  fifteen 


204  OUTLINES   OP   A   SYSTEM   OF 

pounds  per  inch ;  —  raise  it  six  feet,  the  weight  of  the  atmo- 
sphere over  it  has  not  been  increased  ;  its  pressure  remains 
the  same,  but  the  higher  it  is  drawn  the  more  force  has  been 
required  to  lift  it,  and  the  greater  is  the  force  with  which  it 
returns.  The  strength  of  the  "  fuga  vacui "  is  not  there- 
fore caused  by  the  unchanging  weight  of  the  atmosphere. 
It  is  measured  by  the  force  which  produced  the  void  place, 
in  other  words,  by  the  extent  of  the  vacuum,  and  of  course 
does  not  depend  on  the  unvarying  weight  of  the  column  of 
air  over  it. 

To  vary  the  illustration  we  would  refer  to  the  "  Magde- 
burgh  hemispheres,"  as  they  are  called.  Two  hollow  half 
globes  of  metal  are  fitted  to  each  other,  so  that  their  lips 
when  touching  may  be  air-tight.  Exhaust  the  air  within  by 
an  air-pump,  and  then  "  a  force  is  required  to  separate 
them  of  as  many  times  fifteen  pounds  as  there  are  square 
inches  in  the  area  of  the  mouth,  or  at  the  surface  of  the 
division  of  the  upper  and  lower  hemispheres."  The  force 
holding  them  together  is  not  therefore  the  gravity  of  the 
atmosphere  ;  for,  if  the  vacuum  were  perfect,  the  external 
pressure  would  be  in  proportion  to  the  surface  exposed,  —  to 
the  surface  area  of  the  sphere,  not,  as  is  the  case,  to  the  size  of 
the  vacuum  measured  by  its  diameter.  It  is  said  that,  when 
these  hemispheres  were  first  exhibited,  the  inventor  had  a 
pair  made  of  a  foot  in  diameter,  and  that  six  horses  were 
unable  to  pull  them  asunder.  Suppose  the  metal  to  be 
thicker,  so  that  the  vacuum  would  be  only  half  the  size, 
We  know  that  much  less  force  would  be  required  to  pull 
them  apart,  and  yet  the  weight  of  the  atmosphere  around 
them  would  remain  unchanged. 

Thrust  down  a  piston  so  as  to  condense  the  confined  air 
beneath  it,  it  will  be  driven  back  with  the  force  with  which 


MECHANICAL  PHILOSOPHY.  205 

it  was  thrust  down.  Elevate  a  pistoti  so  as  to  rarefy  the  con- 
fined air,  and  it  will  be  drawn  down  with  the  force  with  which 
it  was  elevated.  The  force  of  the  readjustment  is  related 
only  to  the  void  place,  not  to  the  weight  of  surrounding  air, — 
to  the  extent  of  the  disarrangement,  by  no  means  to  the  weight 
of  the  medium  in  which  the  void  place  is  made.  There  is 
one  degree  of  force  pervading  the  atmosphere,  giving  to 
each  of  its  atoms  its  relative  position.  Let  there  be  an 
abnormal  position  of  the  particles  of  any  volume  of  air,  and 
the  force  that  gave  the  normal  position  of  the  atoms,  will  be 
the  measure  of  the  force  required  to  restore  it  to  its  former 
state.  In  other  words,  the  force  of  position  is  invariable. 
But  let  it  be  granted  that  it  is  by  the  pressure  of  the  air 
that  a  vacuum  is  filled,  —  the  pressure  can  be  caused  only 
by  the  elasticity  of  the  air,  or  by  the  power  by  which  it  en- 
larges its  volume  wherever  there  is  space.  If  we  allow  the 
air  to  have  this  elasticity,  every  fact  of  its  action  relative  to 
the  vacuum  is  explained,  and  the  elasticity  could  exist  as 
well  without  as  with  the  attraction  of  the  earth.  Gravita- 
tion therefore  is  not  the  essential  condition  for  the  pressing  of 
the  atmosphere  into  a  void  place.  Elasticity  in  fact  supplies 
a  better  explanation,  and  this  may  exist  without  attraction. 
But  we  consider  the  atmosphere  in  its  normal  state  as 
without  elasticity.  The  action  of  elasticity  being  only  in- 
duced by  a  disturbance  of  the  relative  density  of  its  parts, 
its  action,  so  far  from  being  permanent,  is  remedial,  curative, 
leading  to  equal  diffusion  of  the  atoms  of  the  atmosphere 
through  space.  Therefore  the  air  is  of  uniform  density, — 
therefore  are  the  void  places  filled.  Imagine  in  the  ocean 
an  unfilled  spot,  surrounded  by  water  moving  in  rotation 
with  a  force  of  one  thousand  miles  an  hour,  the  particles  of 
water  not  pressing  on  one  another,  the  force  being  equally 

18 


206  OUTLINES   OF  A   SYSTEM   OF 

diffused,  each  atom  having  its  exact  proportion  ;  —  into 
this  void  place  the  water  will  enter,  and  it  will  be  filled, 
force  diffusing  itself  equally  in  the  whole  stream,  and  at  the 
same  time  equally  diffusing  the  atoms  of  the  stream.  Thus  it 
requires  great  strength  in  the  walls  of  the  vacuum  to  keep 
out  the  flowing  stream  of  air ;  the  force  by  which  nature 
seeks  to  fill  it  is  the  force  by  which  the  matter  of  the  uni- 
verse is  kept  in  constant  motion. 

This  view  impresses  the  mind  with  the  permanency  of 
nature,  with  the  never-varying  intensity  of  her  force. 
However  long  a  vacuum  may  continue,  the  force  of  the 
return  will  be  the  force  of  withdrawal,  and  thus,  while  the 
position  and  movement  of  the  sphere  is  ever  rigidly  deter- 
mined, so  is  the  position  and  movement  of  the  most  minute 
fragment,  of  the  very  atoms  composing  the  fragment,  by  an 
ever  acting,  unchanging  power.  Minor  changes  take  place, 
—  there  is  a  limited  elasticity  which  permits  condensation  and 
rarefaction,  alterations  of  form,  variation  of  motion ;  but  the 
law  preserving  the  general  harmony  is  never  repealed,  —  it 
remains  in  constant  operation.  The  force  that  disarranges 
measures  the  force  which  readjusts  ;  the  void  place  is  filled 
to  restore  perfection,  completeness,  but  never  filled  by  the 
disturbance  of  other  elements.  They  too  have  their  laws,  and 
a  void  in  the  air,  can  be  filled  with  water  to  a  limited  extent 
only ;  for  the  energy  of  nature  is  used  for  preservation  alone. 

In  passing,  we  turn  our  attention  for  a  moment  to  the 
level  of  water  when  in  contact  with  the  atmosphere.  The 
even  surface  of  an  undisturbed  volume  of  water,  —  the  well 
defined  line  which  gives  distinctness  to  the  volumes  of  the 
separate  fluids, —  has  been  usually  traced  to  the  action  of 
gravitation. 

In  speaking  of  chemical  affinity,  we  referred  to  the  equal 


MECHANICAL    PHILOSOPHY.  207 

diffusion  of  force  among  combining  atoms  as  the  necessary 
condition  of  combination.  We  look  upon  matter  as  com- 
posed of  simple  elements,  and  upon  these  elements  as  pos- 
sessing different  relative  capacities  for  the  retention  of  force. 
If  the  simple  elements  in  contact  do  not  equally  diffuse  the 
present  force,  there  cannot  be  the  harmonious  molecular 
action  which  alone  can  unite  them  as  one  mass  or  volume  ; 
if  the  force  be  equally  diffused,  there  ensues  that  sympathy 
of  atomic  action  which  is  the  bond  of  cohesion.  Without 
this  provision  contact  would  determine  combination,  and  in 
the  place  of  established  order,  of  distinctly  characterized 
masses,  all  things  would  be  mingled  in  chaotic  confusion. 
There  would  be 

"  Neither  sea,  nor  shore,  nor  air,  nor  fire, 
But  all  these  in  their  pregnant  causes  mixed 
Confusedly." 

While  we  believe  that  there  is  a  certain  intensity  of  force 
and  its  equal  diffusion,  which  locks  together  the  fitting  ele- 
ments of  every  structure,  —  which  produces  the  various  and 
distinctly  characterized  solids  and  fluids  ;  so  after  their 
construction,  by  the  operation  of  the  same  principle,  are 
they  kept  separate  and  distinct.  Air  and  water,  for  in- 
stance, though  they  may  be  somewhat  mingled  mechan- 
ically, though  for  a  time  their  meeting  surfaces  may  be  to 
a  degree  made  irregular,  continue  to  be  distinct  volumes, 
ever  returning  to  a  fixed  relative  position.  When  at  rest 
their  line  of  separation  is  a  perfect  level ;  the  position  of  one 
is  invariably  above  the  other.  It  is  because  the  one  in  all 
the  transfers  of  force  retains  permanently  the  greater  share, 
that  its  level  of  rotation  is  superior. 

If  a  vessel  containing  water  has  pipes  issuing  from  it  of 
various  shapes  and  diameters,  the  volume  of  water  will  retain 


208  OUTLINES   OF  A   SYSTEM   OF 

the  same  level  in  all  of  its  divisions.  The  water  receives 
that  degree  of  force  only,  which,  while  in  contact  with  air, 
gives  it  its  place  below  the  air,  and  this  force  being  equally 
diffused  throughout  the  volume,  the  force  of  rotation  and  the 
force  of  molecular  action  are  the  same  in  every  part,  resulting 
in  a  uniform  surface  level.  It  is  from  this  principle,  that 
issuing  streams  may  rise  to  the  altitude  of  their  foun- 
tain,—  that  water  running  through  conducting  pipes,  what- 
ever may  be  their  enlargement  or  contraction,  their  length 
or  windings,  knows  the  level  belonging  to  its  volume.  We 
cannot  conceive  of  this  uniform  level  being  produced  by  the 
downward  tendency  of  the  particles  of  the  water.  But  the 
reason  of  it  appears  evident  when  we  consider  it  as  the  outer 
circle  of  rotation,  determinately  fixed  by  the  degree  of  its 
impelling  force.  It  is  from  this  principle  that  the  vast 
ocean,  constituting  almost  a  liquid  world,  though  agitated 
by  winds,  though  swollen  by  tides,  though  traversed  by 
wide-extending  currents,  preserves  the  curve  of  its  sur- 
face,—  the  alternations  marked  upon  its  shores  showing 
that  its  changes,  like  all  changes  in  nature,  are  limited  and 
periodic.  The  ocean  is  not  a  collection  of  particles  gravi- 
tating independently  of  each  other,  nor  is  the  shape  of  its 
volume  preserved  by  the  tendency  of  each  atom  to  the 
centre  of  attraction.  It  is  a  whole,  animated  as  it  were 
with  one  life  diffused  through  every  part, 

An  explanation  of  the  water  level  by  the  theory  of  gravita- 
tion has  been  attempted,  and  the  explanation  has  been  accept- 
ed, not  as  sufficient  and  satisfactory,  but  as  the  best  possible 
in  accordance  with  the  theory.  Suppose  a  vessel  containing 
one  thousand  pounds  of  water,  with  a  pipe  extending  up- 
wards from  its  lower  part  of  a  size  sufficient  to  contain  only 
five  pounds ;  the  water  stands  at  the  same  level  in  both, 


MECHANICAL    PHILOSOPHY.  209 

One  would  suppose  that  the  weight  of  water  in  the  larger 
vessel, — its  constant  tendency  to  descend,  —  would  force  the 
small  quantity  upward  so  that  it  would  escape  from  the  open 
pipe.  Gravitation  asserts  that  the  small  column  is  acted 
upon  only  by  a  column  in  the  large  vessel  of  equal  area  to 
itself,  and  that  all  tfce  water  except  this  column  is  held  in 
place  by  resting  on  the  sides  and  bottom  of  the  containing 
vessel.  But,  as  we  have  seen,  any  downward  force  actually 
applied  to  the  water  is  not  resisted  by  the  vessel,  but  shows 
itself  at  once  by  the  issue  of  water  from  the  orifice.  We 
believe  that  the  same  level  is  maintained  by  both  columns  of 
water,  because  there  is  no  downward  tendency  in  either,  — 
because  the  water  is  one  volume,  and  has  its  rotative  force 
equally  diffused  through  all  its  parts. 

We  pass  to  some  further  considerations  respecting  atmo- 
spheric pressure.  The  theory  of  gravitation  assigns  to  the 
atmosphere,  as  we  have  several  times  had  occasion  to  repeat, 
a  pressure  of  fifteen  pounds  on  every  inch  of  surface  with 
which  it  is  in  contact.  It  therefore  bears  upon  the  body  of 
a  man  of  average  size  with  a  force  of  thirty  thousand  pounds. 
If  this  pressure  were  not  purely  theoretical,  it  would  be  felt. 
We  should  be  conscious  of  it ;  we  should  not  be  compelled 
to  go  to  books  for  our  first  information  respecting  it.  Its 
intensity  would  be  too  great  for  concealment ;  it  would  de- 
clare its  presence  by  its  effects.  That  it  is  not  felt  is 
accounted  for  by  the  assertion  that  it  is  equal  on  every  part 
of  the  body.  "  There  is,"  says  a  popular  writer  on  philo- 
sophy, "  a  difficulty  at  first  in  believing  that  a  man's  body 
bears  this  pressure  while  he  remains  altogether  insensible  to 
it.  But  such  is  the  fact,  and  the  reason  of  his  not  feeling 
it  is  that  it  is  perfectly  uniform  all  around.  Fishes  are  at 

18* 


210  OUTLINES   OF   A   SYSTEM   OF 

ease  in  a  greater  weight  of  water,  and  men  walk  on  the 
earth  without  discovering  a  heavy  atmosphere  about  them, 
which,  however,  will  instantly  crush  together  the  sides  of  a 
square  glass  bottle  emptied  by  the  air-pump,  or  even  of  a 
thick  iron  boiler,  left  for  a  moment  by  any  accident  without 

the  counteracting  internal  support  of  steam  or  air In 

general,  the  pressure  on  one  side  of  a  body  is  balanced  by 
the  equal  pressure  on  the  other,  and  it  is  on  this  account 
that  philosophers  were  so  long  in  discovering  it  at  all,  and 
that  half-informed  persons  are  still  disposed  to  doubt  its 
existence." 

We  must  number  ourselves  with  those  who  still  doubt. 
How  its  uniformity,  its  equal  distribution  on  every  part  of 
the  surface  of  the  body,  exterior  and  interior,  can  destroy 
this  enormous  pressure,  or  rather  how  it  operates  to  prevent 
its  being  sensible,  has  never  been  explained.  The  equality 
of  its  action  could  not  annihilate  the  force.  If  the  air 
presses  on  all  sides  of  the  body,  it  must  press  together  the 
sensitive  particles  constituting  the  body. 

But  it  is  well  known  that  the  human  frame  is  so  consti- 
tuted that  it  is  impossible  for  the  air  to  exert  its  pressure 
uniformly.  There  are  cavities  in  the  body  which  contain 
air.  Now  as  the  pressure  on  the  outside  varies  in  intensity, 
sometimes  a  thousand  pounds  in  an  hour,  according  to  the 
indications  of  the  barometer,  what  is  to  enable  the  small 
quantities  inclosed  to  maintain  so  nearly  a  counteracting 
pressure,  that  in  the  continual  variations  of  weight  outside 
no  sensation  is  perceived  ?  In  the  cavity  of  the  ear,  for 
instance,  there  is  air  which  is  supposed  to  resist  the  outward 
weight ;  but  in  order  to  resist  this  changing  burden,  to 
maintain  the  equilibrium  which  prevents  it  from  being  felt, 
this  internal  air  must  continually  change  its  own  pressure. 


MECHANICAL  PHILOSOPHY.  211 

To  do  this  ifc  must  be  increased  or  diminished,  and  the 
flowing  of  air  into  and  out  of  the  orifice  would  constitute 
it  a  perfect  barometer. 

But  while  some  organs  of  the  body  have  cavities  contain- 
ing air,  which  may  assist  them  in  supporting  the  external 
pressure,  there  are  .-others,  the  brain  for  instance,  which 
have  to  bear  all  the  changes  of  pressure  without  any  internal 
support.  A  well  educated  physician  remarks,  "  How  the 
delicate  organs  of  the  human  body  bear  the  pressure  which 
gravitation  assigns  I  know  not.  It  is  nob  because  of  con- 
tained air  which  resists  the  pressure.  Air  within  the  organs 
would  be  death.  A  very  slight  pressure  on  the  brain, — 
that  of  a  few  ounces  only,  —  is  attended  with  loss  of  con- 
sciousness, yet  the  varying  density  of  the  air  changes  the 
pressure  upon  it  by  many  pounds,  and  I  am  yet  to  learn  that 
the  brain  contains  air,  which,  by  corresponding  changes, 
could  neutralize  the  exterior  pressure." 

But  in  their  eagerness  to  prove  the  existence  of  atmo- 
spheric pressure,  some  philosophers,  forgetting  that  the 
principle  of  -its  equable  pressure  forbids  any  perceptible 
result  from  it,  either  for  good  or  evil,  assert  that  it  exerts 
an  important  influence  on  the  animal  organization.  Doctor 
Arnott,  whom  we  have  before  quoted,  remarks,  "  The  atmo- 
spheric pressure  on  living  bodies  produces  an  effect  which  is 
rarely  thought  of,  namely, — its  keeping  all  the  parts  about 
the  joints  firmly  together  by  an  action  similar  to  that  on 
the  Magdeburg  hemispheres.  The  broad  surfaces  of  bone 
forming  the  knee-joint,  for  instance,  even  if  not  held  together 
by  ligaments,  could  not,  while  the  capsule  surrounding  the 
joint  remained  air-tight,  be  separated  by  a  force  of  less  than 

a  hundred  pounds In  the  loose  joint  of  the  shoulder, 

this  support  is  of  greater  consequence.  ...  In  all  joints  it  is 


212  OUTLINES   OF  A   SYSTEM   OF 

the  atmospheric  pressure  which  keeps  the  bones  in  such 
steady  contact,  that  they  work  smoothly  and  without  noise." 
If  there  is  an  unequal  pressure  on  the  bones  and  ligaments, 
so  there  must  be  on  the  nerves,  veins,  arteries,  and  other 
soft  portions  of  the  body,  for  these  are  as  destitute  of  inter- 
nal air,  enabling  them  to  resist  the  outward  pressure,  as  are 
the  bones  and  joints.  It  is  indeed  strange  that  with  bodies 
so  delicately  organized,  with  perceptions  so  keen  that  the 
slightest  motion  of  the  air,  the  mere  breath  of  the  breeze 
fanning  the  cheek,  is  distinctly  perceived,  we  should  remain 
unconscious  of  this  thirty  thousand  pound  pressure,  or  of  its 
continual  fluctuations. 

We  are  frequently  amused  at  the  effects  which  are  attri- 
buted to  the  variations  of  atmospheric  pressure.  The  city 
of  Cerro  de  Pasca  is  some  fourteen  thousand  feet  above  the 
level  of  the  sea.  Men,  women,  and  children  live  in  this 
city,  and  probably  live  comfortably  there,  notwithstanding 
its  elevated  site.  Cats,  however,  cannot  exist  in  it ;  they 
die  in  convulsions  in  a  few  days  after  being  carried  there. 
And  the  reason  given  to  account  for  this  fact  is,  the  altitude 
of  the  city,  and  the  consequent  rarefaction  of  the  atmo- 
sphere !  Even  Humboldt  gives  this  opinion  the  sanction  of 
his  authority,  although  it  is  well  known  that  the  extent  of 
lungs,  and  consequent  quantity  of  air  received  at  each  in- 
spiration, in  any  species  of  animal,  is  in  proportion  to  the 
vivacity  of  its  movements,  and  of  course  all  animals  would 
equally  feel  the  withdrawal  of  any  portion  of  it.  Therefore 
a  diminution  of  air  that  would  be  fatal  to  cats,  would  be  in- 
jurious also  to  every  other  animal.  Again,  it  has  been 
stated,  that  some  animals  in  the  mountainous  regions  of 
South  America,  when  hunted  by  dogs,  bleed  from  the  mouth 
and  nostrils.  This  also  is  imputed  to  the  extreme  rarity 


MECHANICAL    PHILOSOPHY.  213 

of  the  air.  Are  not  fright,  fatigue,  and  accelerated  circula- 
tion, sufficient  to  account  for  the  fact,  without  referring  it  to 
the  thinness  of  the  air,  especially  when  we  remember  that 
over-driven  horses  at  the  ordinary  level  of  the  earth's  surface 
often  exhibit  the  same  symptom  ? 

It  is  believed  by  many  that  the  sensations  experienced  on 
the  summits  of  very  high  mountains,  are  incontrovertible  proof 
of  the  diminished  density  of  the  atmosphere.  Unquestionably 
the  act  of  ascending  by  personal  effort  to  a  great  altitude, 
affects  the  animal  organization.  It  demands  an  immense 
amount  of  muscular  exertion,  and  it  is  no  wonder  that  the 
effort  is  followed  by  difficulty  of  respiration,  languor,  nausea, 
and  other  uncomfortable  feelings.  Instances  are  given  in 
which  blood  has  gushed  from  the  lips,  eyes,  and  nostrils. 
Humboldt  says,  "  in  the  dangerous  ascent  of  the  mighty 
Chimborazo,  after  incredible  efforts,  at  sixteen  thousand  feet 
elevation,  we  began  to  bleed  at  the  mouth,  nose,  and  eyes." 
It  is  not  wonderful  that,  with  the  full  belief  that  the  air  was 
of  only  half  its  usual  density,  this  fact  should  have  been 
imputed  to  the  removal  of  its  accustomed  pressure  ;  though 
it  is  difficult  to  say  exactly  on  what  principle  a  reduced,  yet 
still  equal  pressure  on  the  whole  body  could  force  the  blood 
from  its  containing  vessels,  though  it  can  readily  be  seen 
that  accelerated  circulation  from  intense  exertion  might  pro- 
duce the  hemorrhage.  Many  a  mouse  has  been  killed  by 
an  air-pump  without  having  its  blood  forced  from  its  mouth ; 
why  should  the  partial  vacuum  of  a  great  altitude  produce 
this  effect  ?  There  is  no  cavity  of  the  human  body  contain- 
ing  air  which  has  not  a  communication  with  the  external  air, 
and  by  the  natural  channels  an  equilibrium  could  be  much 
more  easily  readjusted,  than  by  the  lesion  of  the  blood- 
vessels, 


214  OUTLINES    OF   A   SYSTEM    OF 

In  looking  over  Saussure's  account  of  his  ascent  of  Mont 
Blanc,  we  came  to  the  conclusion  that  it  was  impossible  that 
the  painful  bodily  sensations  which  he  describes  should  have 
been  produced  by  the  rarity  of  the  air.  We  observed  that 
twenty  men  passed  the  night  when  near  the  summit,  crowded 
together  in  a  hole  dug  in  the  snow,  and  covered  with  a  tent- 
cloth  to  protect  them  from  the  intensity  of  the  cold,  thus 
almost  excluding  the  little  air  that  remained  ;  and  that  the 
respiration  of  the  party  at  the  summit,  instead  of  being  more 
full  and  deep,  as  if  nature  would  make  amends  for  the  thin- 
ness of  the  air  by  the  greater  quantity  inhaled,  was  almost 
suspended.  When  Saussure's  attention  was  engrossed  by 
his  barometrical  observations,  he  almost  forgot  to  breathe  ; 
it  was  an  effort,  —  an  act  requiring  the  impulse  of  the  will. 
He  remarks,  "  all  experiments  attended  with  care  caused 
fatigue  in  this  rarefied  air,  and  that  because  without  thought 
you  hold  your  breath"  In  the  descent,  long  before  they 
had  reached  air  of  effectively  increased  density,  all  the 
painful  sensations  ceased.  It  was  the  act  of  descending,  not 
the  level  they  had  reached,  that  was  the  restorative.  Saus- 
sure  accounts  for  the  unexpected  relief  by  saying,  "  As  the 
motion  in  descending  does  not  press  the  diaphragm,  it  does 
not  confine  the  respiration,  and  one  is  not  therefore  obliged 
to  stop  so  often  to  take  breath."  The  party  passed  the 
night  at  a  spot  only  about  six  hundred  feet  lower  than  their 
resting  place  of  the  preceding  night,  where  they  had  expe- 
rienced so  much  suffering.  Saussure  continues,  "We  supped 
with  a  very  good  appetite,  and  I  made  my  observations 
without  any  obstruction  from  indisposition." 

It  is  the  circumstance  of  ascending  by  one's  own  effort 
that  creates  the  bodily  distress.  We  are  supported  in  this 
opinion  by  the  results  of  ascents  in  balloons  ;  for,  though  a 


MECHANICAL  PHILOSOPHY.  215 

greater  altitude  has  been  thus  gained  than  the  highest  moun- 
tain summit  ever  reached  by  man,  and  consequently  the  air 
has  been  according  to  theory  proportionally  diminished  in 
quantity,  yet  the  aeronauts  suffer  no  inconvenience  on  this 
score .  In  a  former  chapter  we  gave  one  authority  for  this  fact ; 
we  will  now  quote  from  Watson's  Practice  of  Medicine.  "  A 
diminution  of  the  circumambient  weight  of  the  atmosphere 
is  supposed  in  some  cases  to  bring  on  hemoptysis.  Blood  is 
said  to  have  been  forced  from  sound  lungs  in  persons  who 
have  ascended  high  mountains,  where  the  atmosphere  is 
rare,  and  where  its  pressure  is  sensibly  lessened.  Perhaps 
the  labor  of  ascent  may  have  shared  in  the  production  of  the 
hemorrhage,  for  I  am  not  aware  that  any  such  effect  has 
ever  occurred  to  persons  who  have  much  more  rapidly 
reached  a  very  great  altitude  in  balloons." 

If  the  painful  sensations  complained  of  were  the  results 
of  a  decreased  supply  of  air  for  respiration,  the  discomfort 
would  be  experienced  by  all  persons,  and  under  all  circum- 
stances, at  the  same  altitude.  The  strong  as  well  as  the 
weak  would  feel  the  loss  of  air,  the  bold  as  well  as  the  timid. 
The  same  altitude  however  differs  in  its  effect  on  different 
individuals,  and  on  the  same  individual  at  different  times. 
We  extract  the  following  passage  from  Ramond's  Ascent  of 
Mont  Perdu,  the  highest  summit  of  the  Pyrenees  :  "  I 
continued  two  hours  on  this  summit,  during  which  time  no 
being  that  had  life  had  come  within  my  sight  except  an 
eagle,  flying  with  inconceivable  rapidity.  We  breathed 
without  any  difficulty  in  this  rarefied  air,  found  by  so  many 
so  insufficient  for  respiration.  I  have  been  myself  more 
than  once  or  twice  witness  to  persons  of  hale  and  vigorous 
constitutions  being  obliged  to  forego  proceeding  to  heights 
much  beneath  this.  Even  Saussure,  upon  the  defile  of  the 


216  OUTLINES    OF  A   SYSTEM   OF 

Giant,  where  the  air  was  by  no  means  so  rarefied,  experi- 
enced an  oppression  of  breathing  by  somewhat  more  than 
common  exertion,  but  here  we  felt  nothing  of  the  kind.  .  .  . 
So  far  from  occasioning  any  weakness,  it  seemed  rather  to 
add  to  my  strength  and  invigorate  my  spirits."  The  only 
effect  of  the  elevation  that  E/amond  specified  was  a  more 
rapid  circulation,  indicated  by  an  acceleration  of  the  pulse, 
and  some  feverish  sensations. 

As  another  confirmation  of  our  views,  we  will  mention 
that  an  athletic  young  friend  of  ours  stated  to  us,  after  read- 
ing Saussure's  account  to  which  we  have  referred,  that  he 
had  experienced  precisely  similar  sensations  while  ascending 
Baldface  Mountain  in  New  Hampshire,  which  is  only  about 
four  thousand  feet  high.  He  thought  several  times  that  it 
would  be  impossible  for  him  to  reach  the  summit,  so  great  was 
his  languor  and  difficulty  of  respiration.  Several  times  he 
was  obliged  to  throw  himself  on  the  ground  in  a  nearly  faint- 
ing state.  These  sensations  he  thought  plainly  attributable 
to  the  difficulty  of  ascent,  not  to  the  rarity  of  the  air.  On 
Mount  Washington,  more  than  two  thousand  feet  higher,  the 
ascent  to  the  summit  of  which  was  accomplished  chiefly  on 
horseback,  the  only  sensation  which  he  experienced  was  that 
of  exhilaration. 

Another  friend  has  given  us  an  account  of  two  ascents  of 
Mount  Washington.  He  remarked  that,  the  first  time,  he 
ascended  on  foot,  and  before  he  had  half  climbed  the  moun- 
tain, each  successive  footstep  painfully  convinced  him  that 
the  air  was  becoming  more  and  more  rarefied.  By  the  time 
he  reached  the  summit,  respiration  was  so  difficult  that  he 
was  rather  surprised  that  the  change  in  the  quality  of  the 
atmosphere  should  be  so  sensibly  felt.  His  second  ascent 
was  on  horseback ;  this  time  he  experienced  none  of  the 


MECHANICAL  PHILOSOPHY.  217 

former  "  asthmatic  breathing,"  and  at  the  summit  "  quite 
forgot  that  he  was  respiring  rarefied  air." 

If  the  quantity  of  air  is  so  seriously  diminished  at  great 
altitudes,  how  is  it  that  large  cities  are  built  at  elevations 
which  ought,  according  to  theory,  to  occasion  great  suffer- 
ing to  their  inhabitants  ?  Among  the  lofty  Andes  are  many 
populous  cities,  enjoying  all  the  luxuries  of  life,  at  heights 
equal  to  that  where  Saussure  and  his  companions  found  it 
so  difficult  to  breathe  on  account  of  the  rareness  of  the  air. 
The  silver  mines  of  Potosi  are  wrought  at  a  height  of  sixteen 
thousand  and  sixty  feet  above  the  level  of  the  sea,  a  height 
nearly  equal  to  the  summit  of  Mont  Blanc ;  and  the  city 
of  Potosi  stands  at  an  elevation  of  thirteen  thousand 
three  hundred  and  fifty  feet  on  the  declivity  of  the  moun- 
tain. The  city  of  Quito,  with  a  population  of  seventy  thou- 
sand, is  nine  thousand  feet  above  the  sea.  Among  the 
Highlands  of  Thibet  also  are  cities  standing  at  great  alti- 
tudes, and  surrounded  with  such  luxurious  vegetation,  that 
Chinese  writers,  it  is  said,  describe  them  as  regions  of 
pleasure.  In  this  connection  we  will  mention  that  a  series 
of  meteorological  observations,  continued  for  twenty-four 
hours  in  succession,  has  recently  been  made  on  one  of  the 
summits  of  this  range,  at  the  height  of  eighteen  thousand  four 
hundred  feet,  where,  according  to  the  barometer,  the  air 
was  of  less  than  half  its  usual  density,  and  "  the  chief  re- 
sult was,  that  the  curves  followed  very  nearly  the  same 
changes  that  they  were  observed  to  do  in  the  lower  regions." 

Vegetation  does  not  appear  to  be  affected  by  altitude  in 
any  other  manner  than  as  the  height  diminishes  the  mean 
temperature.  Different  species  of  plants  become  dwarfed, 
and  then  disappear  as  the  elevation  increases,  just  as  they 
become  dwarfed  and  disappear  as  we  proceed  from  the  equa- 
19 


218  OUTLINES   OF  A   SYSTEM   OF 

tor  towards  either  pole.  In  central  Europe  the  decrease  of 
heat  is  1°  8'  for  every  five  hundred  and  thirty-four  feet  of 
vertical  elevation  ;  an  ascent,  therefore,  of  two  hundred  and 
fifty  feet  is  equivalent  to  a  progress  of  about  one  degree  of 
latitude.  Alpine  plants  are  commonly  covered  with  a  thick 
and  close  down,  which,  as  has  been  remarked,  is  analogous 
to  the  soft  fur  of  northern  animals.  This  Alpine  vegetation 
occurs  at  regularly  decreasing  elevations  as  we  advance 
northward,  and  in  the  Arctic  regions  it  is  the  vegetation  of 
the  plains,  where  the  temperature  is  the  same  as  at  the 
lofty  summits  of  the  equatorial  zone.  The  plants  of  Alpine 
heights  have  been  successfully  cultivated  on  the  plains 
below,  when  due  care  has  been  taken  to  give  them  the 
peculiar  treatment  required. 

But  it  is  supposed  that  the  great  difference  of  atmospheric 
pressure  ought  to  affect  vegetation,  and  consequently  a 
difference  between  plants  indigenous  at  different  levels  has 
been  traced  out.  "  The  influence  of  atmospheric  pressure," 
says  a  distinguished  naturalist,  "  seems  to  me  particularly 
evidenced  in  the  great,  I  may  say  the  prevailing  number  of 
Alpine  species  endowed  with  a  volatile  fragrance,  which 
adds  so  much  to  the  sweet  and  soothing  influence  of  moun- 
tain rambles ;  whilst  the  northern  species,  however  similar 
to  those  of  the  Alps,  partake  more  or  less  of  the  dulness  of 
the  heavy  sky  under  which  they  flourish. "  He  adds,  how- 
ever, "  It  would  be  a  mistake  to  ascribe  to  reduced  atmo- 
spheric pressure  the  peculiar  aspect  of  most  plants  in  the 
higher  Alps."  May  we  not  consider  this  fanciful  proof  of 
the  pressure  of  the  atmosphere,  rather  as  an  expression  of 
the  poetical  idea,  that  science  often  values  the  bouquet  in 
proportion  to  the  labor  of  gathering  it,  and  that,  as  men 
ascend  above  the  defilements  of  earth,  the  sweeter  is  the 
aroma  which  nature  sheds  in  their  path  ? 


MECHANICAL    PHILOSOPHY.  219 

As  we  have  before  said,  Nature,  so  far  from  hiding  from 
view,  throws  herself  open  to  the  sight.  Bj  change  in  the 
mode  of  her  action  she  appears  to  invite  inspection,  —  by 
presenting  herself  under  many  aspects  she  seems  to  courfc 
our  examination.  Were  the  earth  but  one  unvarying  plain, 
many  of  her  processes  which  are  now  fully  exposed,  would 
remain  hidden.  The  mountain  transports  the  northern  vege- 
tation to  the  tropics,  causing  the  polar  plant  to  send  forth 
its  fragrance  under  the  rays  of  the  vertical  sun ;  it  throws 
up  the  strata  of  the  earth,  as  it  were  for  examination ;  it 
collects  together  the  extremes  of  temperature ;  it  places  side 
by  side  the  burning  lava  and  the  never-thawing  snow, — thus 
condensing  world-wide  phenomena,  that  their  relations  one 
to  another  may  be  perceived  at  once.  It  displays  not  only 
physical  results,  but  the  forces  which  control  them,  showing 
us  in  miniature  the  results  of  the  variations  of  rotary  force, 
the  successions  of  climate,  and  the  changes  of  electric  in- 
tensity. Every  fact  therefore  connected  with  the  "  cloud- 
capped  "  mountain,  becomes  full  of  interest  to  all  who  seek 
to  understand  the  organization  of  the  world,  and  to  trace  out 
the  laws  which  govern  its  elements,  —  none  more  so  than 
the  enveloping  wreath  of  vapor  which  has  furnished  its 
poetic  epithet. 

"  In  the  tropical  region  of  Paramos,"  says  Humboldt, 
"  at  an  elevation  of  between  twelve  and  fourteen  thousand 
feet,  some  species  of  large-flowering,  myrtle-leaved  Alpine 
shrubs  are  almost  constantly  bathed  in  moisture,  affording 
evidence  of  the  frequency  of  aqueous  precipitation,  as  do 
the  frequent  mists  with  which  the  lovely  plateau  of  Bogota 
is  covered.  Mists  arise  and  disappear  several  times  in  the 
course  of  an  hour  in  such  elevations  as  these,  and  with  a 
calm  state  of  the  atmosphere.  These  rapid  alternations 


220  OUTLINES    OF    A    SYSTEM    OF 

characterize  the  elevated  plains  of  the  chains  of  the  Andes." 
By  this  condensation  is  furnished  from  the  humid  atmosphere 
the  supply  of  force  required  by  the  high  level  of  the  moun- 
tain, the  moisture  being  brought  to  it  from  the  beds  of  the 
ocean,  which  we  have  described  as  the  storehouse  of  force. 
Every  consideration  is  interesting  which  brings  to  our 
thoughts  that  mighty  Power,  which,  while  it  supplies  the 
wants  of  the  inorganic  world,  provides  also  its  banquet  for 
the  wayfaring  sparrow. 

To  return  from  what  may  appear  a  digression,  —  we  omit, 
for  want  of  space,  a  physiological  view  of  our  subject  which 
had  been  prepared ;  but  we  will  observe  that  it  is  at  once 
apparent,  that  the  act  of  ascending  exhausts  the  strength, 
the  animal  force,  much  more  than  the  same  quantity  of 
muscular  movement  at  one  level.  The  ascent  of  a  single 
flight  of  stairs  is  felt  by  the  weak,  and  the  strongest  expe- 
rience some  difficulty  of  respiration  in  rapidly  mounting 
several  flights  in  succession.  If  we  call  to  mind  the  fact, 
that  the  ascent  of  a  mountain  is  the  act  of  lifting  the  weight 
of  the  body  to  the  whole  extent  of  the  elevation,  —  that  it 
requires  the  rotary  force  for  the  new  level  to  be  supplied,  - — 
we  shall  not  be  at  a  loss  for  the  reason  of  accelerated  respir- 
ation, exhaustion,  and  of  many  other  disturbances  of  the 
animal  functions.  Besides  these,  however,  there  may  be  a 
class  of  sensations  experienced  at  a  very  great  altitude,  the 
cause  of  which  is  independent  of  the  muscular  effort  of  the 
ascent. 

We  know  that  altitude  causes  a  difference  in  the  electric 
condition  of  the  atmosphere  ;  positive  electricity  normally  in- 
creases in  exact  proportion  to  height.  To  the  usual  degree 
of  electricity  the  body  becomes  habituated,  and  an  increase 
or  diminution  of  the  accustomed  quantity  always  affects  the 


MECHANICAL    PHILOSOPHY.  221 

feelings.  If  it  is  lessened,  there  is  a  depression  of  the  ani- 
mal spirits,  while  a  slight  increase  brings  with  it  a  feeling  of 
new  vigor  accompanied  by  exhilaration.  Contrast  the  sensa- 
tions experienced  in  a  warm,  damp  summer-day,  with  those  of 
a  clear,  cold  day  in  mid-winter.  On  the  other  hand,  a  greater 
amount  enervates  the  body  by  a  feverish  increase  of  the  cir- 
culation, and  invariably  diminishes  the  activity  of  the  respir- 
ation. We  know  from  experience  that  an  unusual  electrical 
excitement  of  the  body  has  the  effect  to  enervate  the  body, 
flush  the  cheeks,  and  almost  to  suspend  the  breath. 

The  electricity  of  the  atmosphere,  by  its  fluctuations  at 
the  surface  of  the  earth,  by  its  changes  according  to  eleva- 
tion, and  its  differences  according  to  the  seasons,  in  its  silent 
unobserved  transfers  from  one  element  to  another,  or  in  the 
sudden  loud  explosions  of  the  thunder-storm,  exercises  a 
powerful  influence  on  the  vegetable  and  animal  organization. 
By  tracing  its  effects,  not  only  on  that  which  has  life,  but 
also  on  unorganized  matter,  we  shall  be  able  to  solve  many 
of  the  mysteries  of  nature.  How  much  positive  enjoyment 
might  be  received,  how  much  uneasiness  and  illness  might 
be  avoided,  by  a  recognition  of  the  power  over  the  body, 
exercised  by  the  electrical  states  of  the  elements  about 
us  !  But  this  will  never  be,  so  long  as  gravitation  is 
regarded  as  the  controlling  cause  of  even  bodily  sensations. 
In  a  damp  day,  when  moisture  mingled  with  the  air  strips 
the  body  of  its  accustomed  degree  of  electric  force,  and 
depression  of  spirits  ensues,  we  look  at  the  sluggish  vapor 
resting  on  the  surface  of  the  ground,  and  consider  it  a  proof 
that  the  weight  of  the  air,  its  pressure  upon  the  body,  is 
diminished.  So,  when  the  cheek  is  flushed,  and  the  blood 
leaps  through  the  veins  with  exhilarating  power  on  the 
mountain  height,  we  again  trace  this  opposite  effect  to  the 

19* 


222  OUTLINES    OF   A    SYSTEM    OF 

lessened  pressure  of  the  air.  And  again,  when  by  the  toil 
of  ascent  the  respiration  is  hurried,  and  the  body  sinks  with 
fatigue,  still  no  cause  is  sought  for  all  these  diverse  effects, 
but  the  variations  in  the  space  which  the  atmospheric  par- 
ticles occupy ! 

We  would  mention  another  instance  of  the  tendency  to 
impute  otherwise  unexplained  phenomena  to  alterations  in 
the  pressure  of  the  air.  It  is  well  known  that  the  diurnal 
variations  of  the  barometer  are  in  some  way  connected  with 
the  diurnal  variations  in  the  intensity  of  the  magnetic  force 
as  indicated  by  the  needle.  There  are  every  day  two  maxima 
and  two  minima  of  each,  —  the  maxima  of  one  correspond- 
ing to  the  minima  of  the  other.  There  is  also  a  diurnal 
variation  in  the  tension  of  vapor  in  the  atmosphere  ;  and, 
as  vapor  is  believed  to  change  the  weight  of  the  air,  this  is 
supposed  to  account  for  the  oscillations  of  the  barometer. 
Of  course  then  the  variation  in  the  magnetic  power  is  also 
traced  to  the  state  of  the  atmosphere.  Thus  all  investiga- 
tion seems  to  stay  itself  upon  the  condition  of  the  air,  when 
further  research  most  unquestionably  will  show  that  the  va- 
riations of  the  barometer,  and  of  the  magnetic  force,  and  the 
different  degrees  of  the  tension  of  vapor,  are  traceable  to  one 
cause,  —  to  the  changing  position  of  the  surface  of  the  earth 
with  reference  to  the  centre  of  her  movement,  —  to  the  trans- 
fers of  force  which  preserve  the  equilibrium  of  her  motion. 
These  changes,  as  extensive  as  the  surface  of  the  earth,  cor- 
responding to  her  daily  movements,  varying  too  with  the 
seasons  as  she  traverses  the  different  parts  of  her  orbit,  — 
must  they  not  all  depend  upon  the  same  cause,  —  the  force 
which  controls  her  daily  rotation  and  her  annual  revolution  ? 
The  same  force  which  circulates  through  the  earth  permeates 
the  air,  and  in  its  changes  and  transfers  this  force  must  move 


MECHANICAL    PHILOSOPHY.  223 

the  barometer,  touch  the  needle,  and  determine  the  rise  and 
fall  of  vapor. 

We  asked,  in  a  former  chapter,  why  continue  to  trace  all 
the  phenomena  of  this  beautiful  world  to  one  cause  only, 
and  that  a  cause,  allowing  to  it  all  the  virtue  and  efficacy 
which  it  can  reasonably  claim,  so  inadequate  for  their  expla- 
nation, its  only  legitimate  operation  being  to  determine  the 
position  of  matter,  —  the  point  of  space  which  any  atom 
should  occupy  ?  Does  it  not  repress  inquiry,  and  arrest  the 
mind  in  its  search  after  truth  ?  The  belief  in  the  attractive 
force  of  matter  is  not  only  the  foundation  of  the  structure  of 
our  present  philosophy,  but  it  places  every  stone  of  the  edi- 
fice, and  superintends  even  its  finish  and  its  ornament.  The 
mind  has  no  occasion  to  exert  itself  further.  By  gravitation 
is  explained  the  act  of  drawing  the  first  nourishment,  and 
the  last  expiring  breath ;  the  child  totters  under  it  in  its 
first  attempts  to  walk,  and  old  age  resists  it  with  its  staff. 
We  see  only  this  force  of  senseless  matter  when  the  pendu- 
lum swings,  when  the  stone  falls,  when  the  vessel  floats, 
when  the  vapor  rises,  when  the  clouds  hang  heavy  over  our 
heads.  We  trace  its  effect  in  the  descending  rain,  in  the 
rushing  of  the  mountain  brook,  in  the  flow  of  rivers,  in  the 
swell  of  the  tides,  in  the  outline  of  continents,  in  the  shape 
of  the  earth,  in  the  form  of  her  orbit,  in  the  rush  of  the 
solar  system  through  space.  We  imagine  even  that  by  the 
whirling  of  "  star-dust"  new  worlds  are  gradually  added  to 
the  realm  under  the  sway  of  the  attractive  power  of  inert 
matter ! 

We  pause  for  one  moment  to  glance  back  at  the  extent  of 
ground  over  which  we  have  so  rapidly  passed.  The  facts 
that  we  have  endeavored  to  examine  are  numerous  and 
varied  in  their  character.  Had  we  the  ability,  we  have  not 


224  OUTLINES,   ETC. 

the  space  to  present  them  in  their  fulness  of  scientific  detail, 
nor  is  it  necessary  in  a  treatise  of  this  nature.     But  we 
have  attempted  in  simple  language,  with  the  least  possible 
use  of  technical  phraseology,  to  group  together  many  pheno- 
mena under  a  new  theory  for  their  explanation.     The  result, 
in  spite  of  errors  and  mistakes,  we  hope  may  tend  in  some 
degree  to  strengthen  interest  in  the  works  of  nature ;  for 
in  whatever  light  the  world  is  viewed,  in  whatever  aspect  it 
is  considered,  its  beauty  is  apparent ;  and  though  the  offered 
theory  be  rejected,  it  may  benefit  some  minds  to  forget  for 
a  moment  the  established  explanations  of  things,  that  they 
may  see  creation  with  a  light  from  a  new  direction  touching 
some  of  its  prominent  points.     If  we  have  substituted  for 
logical  deduction  an  allusion  to  the  " laughter"  of  the  exult- 
ing wave,  —  if  in  place  of  the  formula  of  the  mathematician 
we  have  introduced  a  text  of  Scripture,  —  if  we  have  ques- 
tioned the  attractive  power  of  matter,  and  doubted  whether 
it  be  indeed  the  cause  of  all  the  varying  phenomena  about 
us,  —  if  we  refuse  to  admit  the  idea  that  the  universe  exists 
in  its  present  form  from  the  necessity  of  the  case,  because 
it  could  not  be  otherwise  "  considering  the  known  proper- 
ties of  matter,"  — it  is  because  when  we  look  at  nature,  we 
wish  to  see  more  than  the  mere  external  lineaments  ;  —  we 
would  trace  out  the  "Indwelling  Spirit"  which  pervades 
every  part ;   which  is  the  cause  of  all  change,  of  all  move- 
ment ;  which  is  to  the  universe  of  matter  what  the  life  of 
man  is  to  the  body  with  which  he  is  clothed.     We  would  feel 

"  A  presence  that  disturbs  us  with  the  joy 
Of  elevated  thoughts ;  a  sense  sublime 
Of  something  far  more  deeply  interfused, 
Whose  dwelling  is  the  light  of  setting  suns, 
And  the  round  ocean,  and  the  living  air, 
And  the  blue  sky." 


CHAPTER    IX. 


"THOUGH  IT  BE  ONE  OF  THE  MAXIMS  OP  THE  TRUE  PHILOSOPHY, 
NEVER  TO  SHRINK  FROM  A  DOCTRINE  WHICH  HAS  EVIDENCE  ON  ITS 
SIDE,  IT  IS  ANOTHER  MAXIM,  EQUALLY  ESSENTIAL  TO  IT,  NEVER 
TO  HARBOR  ANY  DOCTRINE  WHEN  THIS  EVIDENCE  IS  WANTING." 

Dr.  Chalmers. 

THE  tides  are  often  referred  to  as  a  proof  that  the  law  of 
gravitation  extends  to  the  spheres.  They  are  looked  upon 
as  the  visible  and  tangible  results  of  the  attractive  power 
of  the  sun  and  moon  over  the  waters  of  the  ocean,  —  as  a 
fact  which  appeals  to  the  senses,  —  as  an  evidence  of  the 
doctrine  adapted  to  the  popular  mind.  Without  the  tides, 
it  is  said,  "  the  principle  of  the  universal  attraction  of  matter 
would  rest  solely  on  abstruse  reasoning,  on  abstract  mathe- 
matical deduction.'7  The  tides  indeed  are  presented  by 
many,  as  settling  the  fact,  that  the  law  of  falling  bodies 
extends  upward  to  the  spheres,  giving  them  their  motions 
and  their  mutual  influences. 

But  the  tides  fail  altogether  to  answer  this  purpose  among 
the  unscientific.  It  is  popularly  believed  that  the  sun  and 
moon  are,  in  some  way  or  other,  connected  with  the  phe- 
nomena ;  how,  and  why,  is  not  understood.  There  are 
questions  asked  which  the  books  do  not  answer ;  doubts  en- 
tertained, which  the  theory  of  gravitation  does  not  dissipate. 
There  is  rather  an  acquiescence  in  the  statements  on  this 
subject,  than  a  full  and  hearty  assent.  There  is,  too,  a  wide- 


226  OUTLINES    OF   A    SYSTEM    OF 

spread  rumor  that  philosophy  itself,  with  all  its  strength, 
and  with  all  its  help  from  abstruse  mathematical  reasoning, 
is  baffled  in  the  attempt  to  explain  the  tides  as  a  result  of  the 
law  of  gravitation. 

We  believe  that,  if  the  sun  and  moon  do  attract  the  waters 
of  the  earth,  this  attraction  cannot  produce  the  phenomena 
of  the  tides.  To  strengthen  us  in  this  belief  we  have  high 
authority. 

Professor  Brande  expresses  the  opinion  that  the  collected 
facts  on  this  subject  are  in  advance  of  the  theory  ;  and  that 
these  facts  wait  for  a  more  accurate  determination  of  the 
principles  of  hydrodynamics,  or  the  laws  of  the  motion  of 
water.  La  Place  expressed  the  belief  that  the  collection  of 
more  facts,  at  the  observatory  at  Brest,  a  place  well  adapted 
for  observation,  would  account  for  the  discrepancy  of  the 
theory  with  the  then  established  facts.  Whewell,  in  the 
Philosophy  of  the  Inductive  Sciences,  says,  "  The  tides  are 
a  portion  of  astronomy,  for  the  Newtonian  theory  asserts 
these  curious  phenomena  to  be  the  result  of  the  attraction 
of  the  sun  and  moon.  Nor  can  there  be  any  doubt  but  this 
is  true  as  a  general  statement,  yet  the  subject  to  the  present 
time  is  a  blot  upon  the  perfection  of  the  theory  of  universal 
gravitation,  for  we  are  very  far  from  being  able  in  this,  as 
in  other  parts  of  astronomy,  to  show  that  theory  will  account 
for  the  time,  magnitude,  and  all  the  other  circumstances  of 

the  phenomena  at  every  place  on  the  earth's  surface 

And  what  is  the  portion  of  our  mathematics  which  is  con- 
nected with  this  solitary,  signal  defeat  of  astronomy  ?  The 
attempts  of  the  greatest  mathematicians,  Newton,  Maclau- 
rin,  Bernouilli,  and  La  Place,  to  master  such  questions,  all 
involve  some  gratuitous  assumption,  which  is  introduced  be- 
cause the  problem  cannot  be  otherwise  mathematically  dealt 


MECHANICAL  PHILOSOPHY.  227 

with  ;  these  assumptions  confessedly  render  the  result 
defective,  and  how  defective  it  is  hard  to  say." 

Yet  notwithstanding  that  the  theory  is  thus  questioned 
by  truly  great  men,  it  is  still  presented  to  the  popular 
mind  as  a  proof  of  the  law  of  universal  gravitation.  The 
assumption  that  this  "  blot "  arises  from  defects  in  mathe- 
matical reasoning,  or  from  ignorance  of  the  laws  of  the 
motion  of  fluids,  is  entirely  gratuitous ;  for,  without  re- 
course to  mathematics,  without  the  assumption  of  any  laws 
of  hydrodynamics  except  those  universally  acknowledged, 
the  discrepancy  between  the  facts  and  the  theory  is  fully 
apparent. 

We  would  call  attention  in  the  first  instance  to  this  incon- 
trovertible position.  The  power  of  attraction,  according  to 
the  law  of  gravitation,  and  consequently  the  attraction  of 
any  heavenly  body,  is  inversely  as  the  distance,  and  directly 
as  the  quantity  of  matter ;  or,  popularly,  attraction  decreases 
with  the  distance,  and  increases  with  the  quantity  of  matter. 
If  this  law  is  abandoned,  the  theory  of  gravitation  is  annihi- 
lated at  once  ;  if  it  be  retained,  the  theory  of  the  tides  must 
be  abandoned.  For  the  waters  at  the  surface  of  the  earth 
are  nearest  to  the  earth,  and  the  quantity  of  matter  of  the 
earth  is  as  forty-eight  to  one,  compared  with  the  quantity  of 
matter  composing  the  moon.  Now  with  this  vastly  inferior 
attractive  power,  how  can  the  moon's  attraction  overcome 
that  of  the  earth  ?  How  can  the  moon  raise  the  water  in 
the  least  degree  ?  A  magnet  of  inferior  power  never  de- 
taches a  piece  of  iron  from  a  magnet  of  greater  attractive 
force. 

Again,  if  the  moon  can  raise  the  waters  of  the  ocean  from 
the  earth,  the  attraction  of  the  earth  decreases  as  the  waters 
go  up  from  her  centre,  while  the  attraction  of  the  moon 


228  OUTLINES   OP   A   SYSTEM   OF 

increases  as  they  come  nearer  to  her  centre.  The  idea, 
then,  that  the  moon  can  elevate  the  tidal  wave  one  inch, 
includes  the  idea  that  the  moon  can  draw  the  waters  of  the 
earth  to  her  very  surface,  —  the  grasp  of  the  earth  being 
gradually  relaxed,  and  the  hold  of  the  moon  gradually 
strengthened  as  the  waters  ascend. 

Or  else  there  is  a  focus  or  common  centre  somewhere 
between  the  moon  and  the  earth,  where  the  gravitating 
forces  of  the  two  spheres  produce  an  equilibrium,  and  where 
the  elevated  waters  would  remain,  and  be  at  rest,  —  the 
property  neither  of  the  moon  nor  of  the  earth,  —  belonging 
exactly  to  neither  sphere. 

If  the  moon  attract  the  waters  of  this  globe,  then  she 
attracts  equally  all  the  water  of  one  hemisphere,  the 
hemisphere  nearest  to  her,  and  depresses  equally  all  the 
waters  of  the  other  hemisphere.  We  say  equally,  for  it  is 
so  practically ;  theoretically  the  waters  at  the  point  nearest 
the  moon  would  be  attracted  more  than  the  waters  at 
the  horizon  in  the  proportion  244. OOO2  to  240.0002.  The 
result  of  this  would  be  the  equal  elevation  of  all  the  waters 
of  one  hemisphere,  and  the  equal  depression  of  the  waters 
of  the  opposite  hemisphere  ;  and  this  inequality  of  the  height 
of  the  waters  would  be  propagated  round  the  earth  by  her 
rotation.  The  result  of  this  attraction  by  which  the  earth  is 
forced  to  relax  her  hold  on  a  portion  of  her  waters,  and  in- 
crease the  hold  on  other  portions,  would  be  a  current  of 
water  rushing  round  the  globe  at  the  rate  of  one  thousand 
miles  an  hour. 

The  comparative  power  of  the  sun  and  moon  as  mathe- 
matically deduced  from  their  different  quantities  of  matter 
and  distances,  to  serve  for  the  theory  of  the  tides,  is 
roughly  stated  as  twenty  to  forty-nine.  The  sun,  then, 


OUTLINES   OF  A   SYSTEM   OF  229 

has  less  than  half  the  attractive  power  of  the  moon  at 
the  surface  of  this  globe.  If  the  moon  has  this  superior 
attraction  for  one  purpose,  she  has  it  invariably  for  all  pur- 
poses, and  should  manifest  this  superiority  not  only  in  the 
phenomena  of  the  tides,  but  in  every  phenomenon  con- 
nected with  the  gravitating  or  attractive  power.  The  glo- 
rious luminary,  the  centre  of  attraction  of  all  the  planets, 
so  large  that  if  they  were  united  in  one  mass,  their  aggre- 
gate would  be  to  the  sun  as  a  pebble  to  a  mill-stone,  stands 
aside  shorn  of  his  power,  degraded  to  the  position  of  a  satel- 
lite to  the  moon,  —  his  humble  office,  in  the  words  of  the 
theory,  being  "  to  prime  and  lag "  the  tidal  wave  which 
follows  the  sweep  of  the  majestic  moon  across  the  horizon. 
The  sun,  when  drawing  apart  with  a  force  of  355,000  spheres 
of  the  size  of  the  earth,  manifests  not  even  the  power  to 
uplift  a  little  tidal  wave,  to  follow  in  the  wake  of  the  enor- 
mous wave  of  the  queen  of  the  skies,  the  solar  tidal  wave 
which,  if  he  have  any  power,  should  at  times  follow  the 
lunar  wave  easterly,  and  then  again  westerly  being  never 
seen  ;  for  even  this  little  display  of  force  the  theory  cannot 
allow  him  because  of  stubborn  facts. 

But  let  those  who  uphold  the  theory  proclaim  its  defects 
for  themselves.  It  needs  not  our  aid  to  show  that  it  is 
utterly  insufficient,  and  that  it  is  an  induction  from  the  the- 
ory of  gravitation,  not  a  deduction  from  the  phenomena 
which  the  tides  present. 

We  make  the  following  quotations  from  the  article  on 
tides  in  the  London  Encyclopedia  :  "  The  reader  will  pro- 
bably be  making  some  comparison  in  his  own  mind  of  the 
deductions  of  this  theory  with  the  actual  state  of  things ; 
he  will  find  some  considerable  resemblances,  but  he  will  also 
find  such  great  differences  as  will  make  him  doubtful  of  its 

20 


230  OUTLINES   OF  A   SYSTEM   OP 

justice.  In  very  few  places  does  the  high  water  happen 
within  three  fourths  of  an  hour  of  the  moon's  southing  as 
the  theory  leads  him  to  expect,  and  in  no  place  whatever 
does  the  spring  tide  fall  on  the  day  of  full  and  new  moon, 
nor  the  neap  tide  on  the  day  of  her  quadrature.  These 
always  happen  two  or  three  days  later."  After  referring 
to  some  other  deviations  of  fact  from  theory,  which  devia- 
tions the  writer  accounts  for  by  the  operation  of  local  causes, 
he  continues,  —  "  There  is  also  a  general  deviation  of  the 
theory  from  the  real  series  of  the  tides.  When  the  moon 
enters  her  second  quarter  at  noon,  it  is  high  water  at  Brest 
at  8.40  instead  of  9.48,  which  theory  assigns.  Something 
similar  and  within  a  few  minutes  is  observed  at  every  place 
on  the  sea-coast.  This  is  therefore  general,  and  indicates  a 
real  defect  in  the  theory.  Indeed,  we  have  no  rules  but 
what  are  purely  empyrical,  or  which  suppose  a  uniform 
progression  of  the  tides." 

The  theory  of  the  tides  could  not  stand  for  a  moment 
were  it  not  held  up  by  the  doctrine  of  vis  inertice.  The 
indistinctness  of  this  vis  inertice-  is  a  very  convenient  mist 
to  throw  over  the  defects  of  the  theory.  If  the  flow  of  water 
does  not  show  itself  at  the  right  time,  —  at  the  time  fixed 
by  theory,  vis  inertice  of  rest  holds  the  waters  back ;  on  the 
other  hand,  if  the  flow  arrives  uninvited  by  the  theory,  vis 
inertice  of  motion  brings  the  unwelcome  presence.  This 
vis  inertice  has  been  called  "a  force  of  inactivity,  —  a 
forceless  force,  analogous  to  a  black  white,  a  cold  heat,  and 
a  tempestuous  calm.  For  these  reasons  we  are  inclined 
to  think,"  continues  our  author,  "  that  bodies  are  wholly 
passive,  that  they  endeavor  nothing,  that  they  continue  in 
motion  or  in  rest  by  whatever  begins  the  motion,  and  con- 
tinue to  move  so  long  as  the  cause  continues."  But  the 


MECHANICAL  PHILOSOPHY.  231 

property  of  vis  inertice^  as  we  have  said,  is  convenient  when 
stubborn  facts  will  not  bow  to  the  asserted  theory.  Thus 
the  happening  of  spring  tides  two  or  three  days  after  the 
full  or  new  moon  can  be  accounted  for,  —  the  tidal  wave  con- 
tinuing to  rise  after  the  cause  of  its  rise  is  weakened,  from 
the  habit  which  the  water  has  acquired  of  increasing  its  flow. 
We  copy  the  following  explanation  of  one  of  the  doubtful 
points  in  the  present  theory  of  the  tides,  from  Sir  David 
Brewster's  Life  of  Newton.  "  But  the  most  perplexing 
phenomenon  of  the  tides,  and  one  which  is  yet  a  stumbling- 
block  to  persons  slightly  acquainted  with  the  theory  of 
attraction,  is  the  existence  of  high  water  on  the  side  furthest 
from  the  moon  at  the  same  time  as  on  the  side  next  to  the 
moon.  To  maintain  that  the  attraction  of  the  moon  draws 
towards  herself  and  at  the  same  time  from  herself,  seems  at 
first  sight  paradoxical.  But  the  difficulty  vanishes  when  we 
consider  the  earth,  and  the  waters  on  each  side  of  it  as  three 
distinct  bodies  placed  at  different  distances  from  the  moon, 
and  of  course  attracted  with  forces  inversely  proportioned 
to  the  squares  of  their  distances  ;  the  waters  nearest  the 
moon  will  be  much  more  powerfully  attracted  than  the 
earth,  and  the  earth  more  than  the  waters  farthest  from  the 
moon.  The  consequence  must  be  that  the  waters  nearest 
the  moon  will  rise  from  their  level,  while  the  earth  will  be 
drawn  away  from  the  waters  behind  the  earth,  which  waters 
as  it  were  will  be  left  behind,  and  be  in  the  same  situation 
as  if  raised  from  the  earth  in  a  direction  opposite  to  that  in 
which  they  were  attracted  by  the  moon."  Sir  John  Her- 
schell  explains  the  difficulty  in  a  similar  manner.  Indeed, 
it  is  probably  the  best  solution  that  can  be  given  under  the 
theory  ;  and  it  passes  current  without  examination,  notwith- 
standing its  obvious  defects.  One  would  suppose  that  the 


232  OUTLINES   OF   A   SYSTEM   OF 

earth's  attraction  might  keep  the  waters  at  the  side  opposite 
to  the  moon  close  to  her  bosom,  especially  when  assisted  by 
the  attraction  of  the  moon  drawing  in  the  same  direction. 

Gravitation,  if  we  admit  all  that  is  claimed  for  it,  will  not 
cover  the  phenomena  of  the  tides.  Imagine  a  miniature 
world,  with  its  dry  land,  its  lofty  mountains,  its  wide-spread 
oceans,  and  its  enveloping  atmosphere,  placed  within  the 
sphere  of  the  earth's  attraction.  How  would  the  earth  act 
upon  this  little  world  ?  She  would  draw  it  towards  herself, 
with  a  force  operating  equally  on  its  every  atom.  If  it 
moved  toward  the  earth  through  a  resisting  medium,  the 
more  solid  parts  might  advance  more  rapidly  than  the 
rarer,  —  the  granite  rocks  than  the  thin  air  ;  if  it  moved 
through  void  space,  every  part  would  advance  with  equal 
rapidity,  all  retaining  the  same  relative  position. 

So  if  the  earth  is  attracted  to  the  moon,  every  atom  is 
attracted  ;  and,  if  there  is  any  motion  induced,  every  part 
moves  equally.  Indeed,  astronomers  assert  that  "  the 
earth  is  constantly  falling  to  the  moon,  being  continually 
drawn  by  it  out  of  its  path,  the  nearer  parts  more,  and  the 
remoter  less  so  than  the  central."  But  the  attraction  of  all 
the  particles  of  the  earth  for  each  other,  which  gives  it  its 
form,  —  which  moulds  it  into  "this  goodly  ball,"  is  too 
great  for  the  moon  to  separate  its  elements,  to  tear  it  apart 
as  it  were,  —  to  elongate  its  mass  so  as  to  cause  the  tidal 
flow.  If  the  moon  attracts  the  earth  at  all,  it  must  be  as  a 
whole,  —  as  one  mass.  She  cannot  have  greater  power  over 
one  portion  than  over  another  of  the  earth's  material.  The 
theory  of  gravitation  does  not  give  the  moon  elective  attrac- 
tion, by  which  she  is  enabled  to  move  the  waters  of  the 
ocean,  yet  leave  untouched  the  waters  of  the  great  lakes, 
or  to  lift  the  ocean  and  leave  unmoved  the  bed  on  which  it 


MECHANICAL  PHILOSOPHY.  233 

rests.  And  if  she  can  lift  water  away  from  its  own  centre 
of  attraction,  why  does  she  not  raise  the  sands  of  the 
desert,  the  atmosphere,  vapor,  and  the  descending  rain  ? 
So  evident  is  this  idea,  that  a  scientific  man  in  France, 
after  writing  a  treatise  on  the  tides  in  accordance  with  the 
present  theory,  remarked,  how  strange  it  is  that  the  moon 
should  possess  this  power  over  the  waters  of  the  ocean, 
when  we  know  she  cannot  draw  towards  herself  a  feather 
floating  above  them ! 

The  extension  of  the  law  which  is  supposed  to  determine 
the  fall  of  bodies,  into  a  universal  principle  pertaining  to 
all  matter,  is  considered  as  one  of  the  most  important 
achievements  of  philosophy.  The  great  glory  of  the  theory 
is  its  universality, — the  extent  of  ground  which  it  covers. 
The  tendency  of  philosophy  therefore  is,  never  to  narrow 
its  range,  but  by  all  possible  means  to  extend  its  applica- 
tion. A  fact  that  has  once  passed  under  its  sway  is  held 
with  a  tenacious  grasp.  It  is  withdrawn  from  farther 
examination. 

The  theory  of  the  tides  is  an  instance  of  this.  The  tidal 
wave  rises  up  against  the  very  law  of  falling  bodies ;  it 
escapes  from  the  attraction  of  the  earth.  Looking  upward, 
astronomy  sees  the  moon,  a  smaller  body  than  the  earth,  at 
a  great  distance  from  it,  and  endows  her  with  power  to 
overcome  the  attraction  of  the  greater  earth,  as  regards  the 
waters  lying  upon  her  very  bosom.  The  mathematician  can- 
not reconcile  the  theory  with  facts,  the  scientific  man  looks 
incredulous  when  he  teaches  the  doctrine,  and  plain  com- 
mon sense  absolutely  refuses  to  believe  it.  Thus  it  remains 
a  doctrine  assented  to,  but  not  believed,  —  asserted  with- 
out being  fully  comprehended,  —  declared  by  men  of  the 
strongest  minds  to  be  a  "  Uot"  upon  the  theory  of  univer- 

20* 


234  OUTLINES   OF   A    SYSTEM   OF 

sal  gravitation.  Why  not  boldly  abandon  the  theory,  and 
seek  for  a  better  ?  Facts  will  not  support  it,  and  facts  never 
change  their  argument.  They  will  not  do  in  the  future  what 
they  have  refused  to  do  in  the  past. 

Our  knowledge  of  the  great  tidal  waves  of  the  ocean  is 
gained  only  through  the  facts  presented  by  the  tidal  ebb 
and  flow.  The  swelling  and  shrinking  of  the  ocean  is  too 
small  compared  with  the  extent  of  its  surface  to  be  percep- 
tible ;  for  above  its  vast  expanse  there  is  no  fixed  point  by 
which  to  measure  its  altitude.  But  on  the  coasts  the  con- 
sequent currents  are  noticed,  and  the  rise  and  fall  of  the 
waters  can  be  measured.  Only  by  these  changes  of  level 
on  the  shores,  are  the  alternations  of  the  great  deep  made 
known.  It  is  the  tidal  ebb  and  flow  which  indicate  the 
character  of  the  tidal  wave  producing  them. 

The  ebb  and  flow  both  continue  for  six  hours,  that  is, 
from  elevation  to  elevation,  and  from  depression  to  depres- 
sion, there  is  an  interval  of  twelve  hours.  This,  however, 
would  bring  the  time  of  high  water  to  the  same  hour  every 
day  ;  but  in  addition  to  the  regular  interval,  a  half  rotation 
of  the  globe,  there  is  a  lapse  of  time  between  the  tides,  occa- 
sioning what  is  called  their  progression,  which  continually 
retards  the  time  of  high  water  to  that  degree  that  the  pro- 
gression completes  its  period,  and  the  phases  of  the  tides 
complete  their  revolution,  returning  to  the  same  hour,  in  one 
lunation,  or  in  the  time  of  one  revolution  of  the  moon.  The 
tide  commences  its  flow  sluggishly,  gradually  increasing  its 
velocity  until  towards  high  water ;  it  then  slackens  its  speed, 
and  when  the  full  height  is  attained,  it  pauses  awhile  until 
the  depression  of  the  great  tidal  wave  recalls  the  waters, 
which  in  their  ebb  manifest  the  same  increase,  diminution, 
and  cessation  of  current. 


MECHANICAL  PHILOSOPHY.  235 

These  are  the  daily  phenomena  of  the  tides,  the  extent  of 
their  flow  and  the  direction  of  the  currents  being  somewhat 
modified  by  local  and  temporary  causes,  such  as  the  con- 
figuration of  the  coast,  and  the  force  and  direction  of  the 
winds.  Besides  these  irregular  and  occasional  fluctuations, 
there  are  also  periodical  changes  which  are  important,  as 
they  point  to  the  nature  and  character  of  the  producing 
cause  of  the  tidal  wave.  These  periodical  variations  are 
governed  by  the  seasons  of  the  year,  by  the  position  of  the 
moon  in  relation  to  the  earth,  and  by  the  hour  of  the  day  at 
which  high  water  occurs.  The  greatest  or  spring  tides  take 
place  two  or  three  days  after  the  new  and  full  moon,  and 
the  smallest  or  neap  tides  at  about  the  same  lapse  of  time 
from  the  quadratures.  There  is  also  a  difference  between 
the  day  tides  and  the  night  tides,  and  between  those  of 
summer  and  of  winter. 

To  obtain  a  distinct  view  of  this  subject  we  must  separate 
the  effect  from  the  cause,  —  the  current  running  to  and  from 
the  coast,  increasing  and  diminishing  the  waters  in  bays  and 
harbors,  from  the  elevation  and  depression  of  the  ocean  ;  we 
must  distinguish  the  tidal  flow  from  the  tidal  wave  ;  for  they 
are  separate  and  distinct  in  their  character.  The  great 
tidal  wave  is  the  vertical  elevation  of  the  waters  of  an 
ocean,  —  the  tidal  flow  is  merely  a  surface  current,  running 
on  an  inclined  plane,  at  the  rate  of  a  few  miles  an  hour  ; 
and  as  the  tidal  wave  by  its  rise  or  fall  changes  the  inclina- 
tion of  the  plane,  the  consequent  current  changes  the  direc- 
tion of  its  flow.  The  tidal  flow  therefore  is  the  result,  not 
the  cause,  of  the  alternations  in  the  level  of  the  ocean. 
Compared  with  the  great  oceanic  currents,  the  immense 
westerly  current  of  the  tropics  and  its  branches,  and  the 
polar  currents,  the  tidal  flow  is  utterly  insignificant.  But 


236  OUTLINES    OF   A   SYSTEM   OF 

all  these  mighty  ocean  currents  are  lifted  up  with  the  great 
tidal  waves. 

To  form  these  waves  the  ocean  waters  of  the  two  opposite 
hemispheres  are  elevated,  and  there  is  an  accompanying 
depression  at  the  equidistant  points  ;  and  by  the  rotation  of 
the  world  each  part  of  its  surface  shares  in  the  alternations. 
The  question  is,  what  is  the  impulse  of  this  vast  oscillation, — 
what  the  dynamic  power  for  this  alternate  rise  and  fall  of 
the  waters  of  the  globe  ?  The  even-balanced  sea,  though 
so  free  to  move,  does  not  of  itself  lift  and  depress  its  volume. 
There  is  a  moving  power,  —  an  impulse  which  gives  the 
mighty  motion.  As  winds  in  passing  over  the  surface  of  the 
sea  form  minor  waves,  so  is  there  some  force  which  pene- 
trates the  waters,  stirring  them  to  this  vast  tidal  pulsation, 
swelling  and  shrinking  them  on  every  shore,  in  the  bays  and 
harbors  of  every  coast.  So  that  instead  of  a  dead  level,  or 
a  level  storm-disturbed  only,  there  are  ever  varying  and 
periodic  alternations  of  surface,  ministering  to  the  wants  of 
man,  and  presenting  to  him  one  of  the  most  interesting 
phases  of  the  "  life  of  the  world." 

In  all  oscillatory  movement,  as  in  the  swing  of  a  pendu- 
lum, there  is  a  transfer  of  force  according  as  the  level 
changes.  The  descending  water  gives  out  the  no  longer 
needed  force  of  rotation  to  the  water  rising  to  the  higher 
level,  the  mean  altitude  and  the  mean  degree  of  force  re- 
maining ever  the  same.  But  oscillation  does  not  furnish  its 
own  impulse.  To  account  for  the  tidal  wave,  we  must  recur 
to  a  regular  and  periodic  passage  of  force  which  touches  the 
waters,  imparting  to  them  their  motion. 

The  force  which  causes  the  tidal  swell  must  be  of  varying 
intensity.  We  refer  not  to  local  and  occasional  changes, 
but  to  periodic  alternations  in  its  strength.  The  motive 


MECHANICAL   PHILOSOPHY.  237 

power  of  the  tides  varies  in  degree  according  to  the  position 
of  the  part  of  the  earth  at  which  it  is  high  water  in  relation 
to  the  centre  of  her  orbit ;  it  varies  according  to  the  position 
which  the  earth  occupies  in  her  orbit,  and  her  position 
in  relation  to  the  moon.  In  other  words,  the  hour  of  the 
day,  the  season  of  the  year,  and  the  phases  of  the  moon 
point  to  the  changes  in  the  intensity  of  the  impelling  force 
of  the  tidal  oscillation.  It  is  then  connected  with  the  earth's 
motion  ;  it  is  a  branch  of  the  same  force.  It  comes  there- 
fore from  that  which  is  world-wide  in  its  action,  from  that 
which  increases  and  diminishes  the  great  movement  of  the 
earth  ;  for  we  trace  all  its  changes  to  the  perturbations  and 
vicissitudes  of  her  rotation  and  revolution. 

The  force  of  terrestrial  magnetism  was  formerly  supposed 
to  be  of  limited  and  partial  action,  —  to  pertain  to  a  class 
of  metals  only ;  but  recent  discoveries  prove  the  universality 
of  its  power  over  every  kind  of  matter  of  which  the  world  is 
composed.  The  oxygen  of  the  atmosphere  has  been  recently 
proved  to  be  the  subject  of  its  power  ;  and  certain  crystals 
suspended  by  a  thread  of  silk  are  found  "  to  take  under  the 
direction  of  the  earth's  magnetism  a  determinate  and  fixed 
direction,"  acting  as  magnetic  needles,  "  pointing  constantly 
towards  the  poles  of  the  earth,  towards  the  magnetic  poles, 
or  toward  some  azimuthal  point."  The  transfers  of  elec- 
tricity, once  considered  as  the  passing  of  matter  from  the 
positive  to  the  negative  electric  state,  are  now  regarded 
as  the  plus  and  minus  in  the  present  quantity  of  a  pervading 
power,  and  electrical  phenomena  are  deemed  the  evidence 
of  a  restoration  of  the  equilibrium  of  force.  Philosophy 
recognizes  a  force  flashing  through  the  sea,  permeating  the 
atmosphere,  and  penetrating  into  the  solid  earth. 

Nor  is  this  force  spasmodic  and  irregular  in  its  transits. 


238  OUTLINES   OP  A   SYSTEM  OF 

There  are  permanent  currents  indicated  by  the  magnetic 
needle  ;  for  the  constant  action  of  the  needle  can  be  caused 
only  by  a  continued  flow  of  the  galvanic  stream  ;  nor  is  the 
flow  of  uniform  intensity,  but  it  is  subject  to  regular  and 
periodic  alternations  of  strength.  Between  the  tropics, 
where  by  the  greater  diameter,  and  the  consequently  greater 
degree  of  rotary  force,  the  electrical  and  magnetic  pheno- 
mena are  more  fully  developed,  the  hour  of  the  day  can  be 
determined  "  by  the  position  of  the  needle,  as  well  as  by 
the  changes  of  the  barometer."  Humboldt  believes  in  the 
existence  of  many  systems  of  magnetic  currents  ;  he  de- 
scribes the  incessant  oscillation  of  all  magnetic  phenomena 
"  according  to  the  hours  of  day  and  night,  and  according  to 
the  seasons  of  the  year,  and  according  to  the  whole  course 
of  the  year,"  so  that  we  are  compelled  to  believe,  that  there 
are  regular  and  constant  transmissions  of  force  around  the 
world,  to  preserve  the  equilibrium  of  motion  between  the 
different  parts,  as  by  their  changing  position  there  is  a 
necessary  acceleration  or  retardation  of  their  velocity, 

In  our  remarks  on  the  barometer  we  referred  to  the  oscil- 
lation of  the  earth's  circumference,  by  which  there  was  at 
the  opposite  points  an  enlargement  of  the  diameter,  and  a 
contraction  at  the  intermediate,  equidistant  points.  It  is 
not  the  barometer  only  which  indicates  this  fact.  The 
action  of  the  needle  strengthens  us  in  this  opinion.  If  there 
is  this  swelling  and  shrinking,  there  are  parts  of  the  globe 
which,  by  their  wider  orbit  of  rotation,  would  require  the 
greater  force  of  propulsion,  and  parts  which  by  their  subsi- 
dence would  require  the  less.  There  must  needs  be  a 
transfer  or  passage  of  force,  and,  the  action  of  the  needle 
being  determined  by  the  current  of  force,  this  transfer 
would  be  indicated  by  its  movements.  Accordingly  we 


MECHANICAL    PHILOSOPHY.  239 

find,  that  the  needle  has  its  two  maxima  and  minima  of 
horizontal  intensity,  corresponding  to  the  maxima  and  min- 
ima of  the  barometer,  coinciding  with  noon  and  midnight, 
morning  and  evening.  In  the  transfers  of  force  to  preserve 
the  equilibrium  of  motion,  the  current  would  be  the  strongest 
and  the  weakest  at  the  points  indicated  by  the  correspond- 
ing degrees  of  magnetic  intensity  ;  at  those  parts  the  barom- 
eter indicates  the  greatest  change  of  level,  which  causes  this 
transfer  of  the  force  of  rotation. 

Again  ;  there  is  another  manifestation  of  the  need  of  more 
and  of  less  force  at  these  opposite  points  of  the  earth,  from 
the  differing  degrees  of  the  intensity  of  the  tension  of  vapor. 
Without  any  known  cause,  water  at  certain  times  passes  into 
vapor,  and  at  others  the  vapor  condenses  under  the  same  de- 
gree of  temperature.  Besides  the  occasional  and  irregular 
exhibitions  of  this  phenomenon,  there  are  also  periodic  alter- 
nations, corresponding  with  the  hour  of  the  day  or  night. 
The  tension  of  vapor  has  also  its  two  maxima  and  minima, 
corresponding  to  those  of  the  barometer  and  the  compass.  We 
believe  that  this  alternation  is  governed  by  the  need  of  more 
or  less  force  of  rotation  of  the  several  parts  of  the  earth. 
When  force  is  required  the  vapor  condenses,  —  when  it  is 
super-supplied,  the  water  passes  into  vapor.  We  have  re- 
peatedly referred  to  this  as  one  of  the  means  by  which  the 
equilibrium  of  motion  is  maintained.  At  first  sight,  the 
influence  of  this  alternate  vaporization  and  condensation  may 
appear  of  little  value ;  but  on  the  great  scale  of  nature's 
works,  with  the  wide  expanse  of  the  surface  waters  of  our 
globe,  it  is  indeed  a  vast  agency.  It  has  been  supposed  that 
vaporization  and  condensation  were  determined  directly  or 
indirectly  by  temperature  ;  but  how  can  this  be  when  vapor 
is  formed  alike  under  the  vertical  sun  of  the  tropics  and  from 


240  OUTLINES   OF  A   SYSTEM   OF 

the  frozen  oceans  of  the  poles,  snow  and  ice,  as  well  as  the 
warmest  surface  water,  throwing  off  vapor  which  condenses  at 
times  in  all  altitudes,  and  under  every  degree  of  sensible  heat. 

The  temperature,  positive  or  relative,  produced  by  the 
sun's  rays,  appears  altogether  insufficient  as  the  direct  or 
indirect  cause  of  the  passage  of  the  currents  of  force.  It 
cannot  explain  the  maxima  and  minima  of  the  barometer,  of 
the  needle  and  of  the  tension  of  vapor,  any  more  satisfacto- 
rily than  it  could  explain  the  two  daily  maxima  and  minima 
of  the  tides.  The  sun's  influence  changes  the  temperature 
of  the  earth  only  a  few  feet  beneath  its  surface,  and 
the  temperature  varies  according  to  elevation  ;  yet  the 
barometer,  whether  suspended  over  sunny  plains  or  carried 
to  the  summits  of  snow-clad  mountains,  notes  equally  the 
diurnal  changes  ;  and  the  needle  in  caves  or  mines,  where 
the  thermometer  shows  that  the  solar  influence  never  pene- 
trates, records  the  hourly  increase  or  diminution  of  the 
magnetic  stream  by  which  its  motions  are  governed.  Mag- 
netic storms  also  pass  over  vast  portions  of  the  earth,  disturb- 
ing the  regular  action  of  the  magnetic  needle,  whatever  may 
be  its  altitude  of  position  or  the  surrounding  temperature ; 
and  if  the  needle  is  affected  all  over  the  world  thus  simulta- 
neously by  magnetic  storms,  surely  that  which  causes  its 
regular  action  has  an  equal  range,  —  a  range  far  too  vast 
to  owe  its  power  to  changes  of  temperature,  which  from 
their  nature  are  limited  and  local.  If  the  perturbations  of 
the  needle  are  world-wide,  so  is  the  cause  of  its  normal 
action. 

Unquestionably  all  these  phenomena,  constituting  the 
threefold  manifestation  of  the  transfer  of  force,  are  connected 
with  heat,  —  not  with  heat  from  solar  influence,  but  with  the 
sensible  heat  evolved  by  the  passage  or  readjustment  of  the 


MECHANICAL  PHILOSOPHY.  241 

magnetic  force.  The  temperature  of  soft  iron  is  raised  by 
the  process  of  infusing  into  it  the  magnetic  power  ;  the  heat 
of  the  earth,  below  the  surface  at  least,  we  believe  is  deter- 
mined by  its  degree  of  magnetic  force ;  the  magnetic  poles 
are  the  poles  of  extreme  cold.  Transfers  cannot  take  place 
without  indicating  that  heat  is  another  term  for  the  force  of 
motion.  "  Terrestrial  magnetism,"  says  Humboldt,  "  stands 
in  most  intimate  relation  with  the  internal  as  well  as  the  ex- 
ternal heat  of  our  planet But  the  old  explanation  of 

the  horary  variations  by  the  progressive  warming  of  the 
earth  by  the  rotation  of  the  world,  must  be  limited  to  its  upper 
surface."  For  the  solar  heat  and  the  consequent  changes 
of  temperature  do  not  always  reach  the  instruments  which 
alternate  in  their  action.  They  are  touched  and  moved  by 
the  force  of  terrestrial  magnetism,  and  their  variations 
record  the  changes  in  the  intensity  of  its  passing  currents. 
But,  besides  the  transfer  of  force  for  the  adjustment  of 
the  rotary  motion  of  the  parts  of  the  earth,  which  by  the 
oscillation  of  surface  need  the  greater  or  the  less  degree, 
there  is  another  flow  of  the  magnetic  power  to  restore  the 
equilibrium  of  the  earth's  motion  in  her  orbit  of  revolution. 
They  both  affect  the  needle,  combining  to  produce  its  varied 
phenomena  as  well  as  the  many  meteorological  changes 
and  vicissitudes,  which  present  the  action  of  the  two  causes  in 
various  degrees  of  relative  intensity.  This  globe  requires 
less  of  the  force  which  impels  her  in  her  orbit  at  some  parts 
than  at  others.  The  point  nearest  the  centre  of  revolution 
describes  an  orbit  eight  thousand  miles  less  in  diameter  than 
the  point  which  is  the  most  remote,  and  generally  one  hemi- 
sphere needs  less  of  the  force  of  motion  than  the  other. 
The  rotation  of  the  earth  continually  changes  the  position  of 
every  part  in  relation  to  the  centre  of  the  orbit.  There  is, 
21 


242  OUTLINES   OF   A   SYSTEM   OF 

therefore,  a  constant,  unremitting  passage  of  force  from  one 
part  to  the  other,  from  one  hemisphere  to  the  opposite. 
This  which  for  the  want  of  a  better  name  we  call  the  spare 
force  of  revolution,  we  consider  as  the  motive  power  of  the 
tides,  —  as  the  impulse  which  causes  the  oscillation  of  the 
great  deep. 

That  there  is  this  passage  of  electrical  or  magnetic  force 
around  the  globe  is  acknowledged  ;  and  it  seems  evident 
that  it  cannot  be  caused  by  the  progressive  warming  of  the 
surface  of  the  earth.  If  we  are  right  in  our  conceptions  of 
the  nature  of  force,  a  flow  must  be  produced  by  the  unequal 
orbits  described  by  the  different  parts  of  the  earth,  as  they 
are  more  or  less  distant  from  the  centre  of  revolution. 
This  inequality  appears  to  us  sufficient  to  produce  a  transfer 
that  would  account  for  the  results  which  we  impute  to  it ; 
for  there  are  instruments  of  such  delicacy,  as  to  detect  a 
variation  of  one  forty-thousandth  part  of  the  magnetic  inten- 
sity, and  surely  nature  would  register  in  her  phenomena  the 
differences  in  the  degree  of  required  force  in  orbits  which 
vary  eight  thousand  miles  in  diameter. 

There  is  another  consideration  which  supports  our  belief 
in  the  reality  of  this  transfer  of  force.  It  is,  if  we  may  be 
allowed  the  expression,  the  necessity  of  a  life-giving  circula- 
tion, to  impart  to  the  face  of  nature  its  ever-varying  beauty, 
to  produce  those  changes  and  vicissitudes  which  minister  to 
the  enjoyment  of  life,  and  to  create  that  ceaseless  activity  of 
the  elements  which  brings  the  world  into  sympathy  with  the 
activity  of  living  beings.  Without  this  it  would  seem  as  if 
all  things  would  harden  into  monotony,  and  the  power  now 
so  fully  exhibited  in  exciting  and  controlling  the  elements, 
would  be  hidden  by  the  dull,  unvarying  uniformity  of  its 
action.  We  live  in  a  world  of  change,  but  of  change  so  lim- 


MECHANICAL  PHILOSOPHY.  248 

ited  that  the  storm  only  heightens  the  enjoyment  of  the  calm, 
while  it  has  power  and  beauty  of  its  own,  —  of  change  so 
limited,  that  instead  of  manifesting  chance,  it  unfolds  de- 
sign, the  cycle  of  vicissitudes  showing  the  steadfastness 
of  the  Hand  which  governs  them. 

Our  belief  in  the  necessity  of  this  constant  transfer  of 
force  is  further  supported  by  considerations  drawn  from  the 
arrangements,  by  which  activity  of  motion  is  produced  in  the 
other  planets  belonging  to  the  solar  system.  The  strength 
of  this  flow  of  force  is  governed,  not  only  by  the  diameter  of. 
the  sphere,  but  also  by  the  proportion  which  this  diameter 
bears  to  the  diameter  of  the  orbit.  That  each  world  may 
have  a  sufficient  current  of  force  circulating  through  its 
several  parts  to  produce  the  necessary  alternations,  and  yet 
these  alternations  be  kept  within  such  bounds,  that  life  and 
the  enjoyment  of  life  may  be  secure,  the  diameters  of  the 
planets  increase  as  their  orbits  enlarge,  and  by  the  addition 
of  satellites,  and  by  the  increased  number  of  these  attendant 
spheres,  as  well  as  by  the  wider  sweep  of  their  orbits,  the 
extreme  points  of  each  local  system  are  more  widely  sepa- 
rated as  their  distance  from  the  centre  increases,  and  an 
equality  in  the  transfers  of  force  is  maintained  among  them 
all.  This  is  the  case  with  all  the  planets,  except  the  sys- 
tem of  smaller  spheres  between  the  Earth  and  Jupiter.  The 
Asteroids  have  a  greater  eccentricity  than  the  other  planets, 
and  by  the  greater  inclination  of  their  orbits  revolve  in  a 
different  plane,  which  may  perhaps  stand  in  the  place  of  the 
greater  diameter.  Were  Jupiter  placed  next  the  Sun,  the 
wide  distance  between  its  extreme  parts  would  bear  too  great 
a  proportion  to  its  distance  from  the  centre  of  its  orbit. 
The  different  degrees  of  force  needed  by  the  parts  at  the 
outer  and  inner  circumference  of  the  orbit,  would  cause  too 


244  OUTLINES    OF   A   SYSTEM   OF 

rapid  transfers  ;  while  Saturn,  at  his  distance,  can  bear  the 
enlargement  of  diameter  caused  by  his  rings  ;  and  perhaps 
in  far-off  Uranus  the  retrograde  movements  of  his  satellites 
gives  the  required  inequality.  Nor  can  we  fail  to  remem- 
ber, that  the  outermost  planets  have  the  greatest  velocity  of 
rotation. 

Returning  to  the  consideration  of  our  own  planet,  we  find 
not  only  the  transfer  of  force  which  is  due  to  her  diameter, 
but  also  those  variations  of  its  intensity  which  proceed  from 
,  eccentricity  of  orbit,  and  from  the  action  of  her  satellite. 
The  motion  of  the  earth  in  her  orbit  is  not  of  uniform  velo- 
city, nor  does  her  distance  from  the  sun  always  remain  the 
same.  Hence  the  increase  and  diminution  of  the  transfer 
of  force  is  dependent  on  the  season  of  the  year  ;  hence  has 
the  needle  its  two  annual  maxima  and  minima  ;  hence  the 
yearly  barometrical  changes,  and  the  different  degrees  of 
the  tension  of  vapor.  The  maxima  and  minima  of  the  year 
correspond  to  summer  and  winter,  spring  and  autumn,  as 
those  of  the  day  to  noon  and  midnight,  and  morning  and 
evening.  Thus  "  all  things  are  double  one  against  another, 
and  He  hath  made  nothing  imperfect.  One  thing  estab- 
lisheth  the  good  of  another." 

There  can  be  no  independent  change  of  motion  in  any 
mass  or  any  sphere.  The  force  which  one  receives  another 
surrenders.  All  things  therefore  move  sympathetically,  — 
there  is  no  isolation  in  any  part  of  the  universe.  The 
spheres  move  in  unison,  as  if  connected,  (as  the  idea  has 
been  expressed  by  another,)  by  elastic  material  ties.  Dis- 
believing altogether  in  the  attractive  and  repulsive  power  of 
matter,  we  regard  the  universe  as  one  great  whole,  its 
separation  into  parts  in  man's  mind  being  only  because  he 
must  divide  in  order  that  he  may  comprehend. 


MECHANICAL    PHILOSOPHY.  245 

If  the  heavenly  bodies  generally  move  thus  in  sympathy, 
if  the  vibration  of  the  more  distant  stirs  the  force  that  gives 
the  complementary  oscillation  to  the  others,  —  how  much 
greater  the  mutual  influence  between  planets  and  their 
satellites,  whose  relations  seem  designed  to  increase  and  to 
vary  the  strength  of  the  life-giving  flow  of  force ! 

The  relation  of  the  moon  to  the  earth  is  not  thus  intimate 
because  of  her  nearness  of  position  only.  We  regard  the 
moon  as  a  part  of,  as  pertaining  to,  this  globe ;  we  consider 
them  as  together  constituting  one  member  of  the  solar  sys- 
tem, revolving  together  around  their  common  centre.  The 
moon  is  not  an  independent  mass  wrapped  up  in  herself  by 
an  individual  rotation,  as  if  a  separate  value  were  included 
within  her  own  diameter.  Her  secondary  movement  is 
round  the  earth  as  her  centre.  It  is  true,  as  astronomy 
asserts,  that,  in  passing  round  the  earth,  she  turns  in  relation 
to  a  point  in  space.  So  does  every  mountain  on  the  face  of 
the  earth.  Mont  Blanc  turns  in  relation  to  space  once  for 
every  diurnal  revolution  of  the  earth,  otherwise  its  base  would 
not  rest  on  the  earth,  and  its  summit  point  continually  from 
it.  So  the  moon,  because  she  turns  in  relation  to  space, 
keeps,  —  her  libration  excepted,  —  the  same  hemisphere 
always  directed  towards  this  globe.  We  repeat  the  idea  ; 
she  does  not  by  an  independent  rotation  wrap  up  an  inde- 
pendent value  in  her  diameter. 

Besides,  in  the  associated  motion  of  the  earth  and  moon 
around  their  common  centre,  there  is  between  them  a  point 
of  equilibrium  which  describes  the  true  ellipse  of 'their  com- 
mon orbit.  This  point  of  space,  which  would  be  the  true 
position  were  the  masses  united,  is  near  the  actual  line  of 
the  motion  of  both  at  the  moon's  quadratures  ;  at  the  new 
and  full  moon  they  are  both  at  the  greatest  distance  from 

21* 


246  OUTLINES   OF   A   SYSTEM   OF 

the  mean  orbit.  Hence  come  the  monthly  periodical 
changes  of  the  earth's  motion,  and  with  these  changes  the 
periodical  increase  and  diminution  of  the  flow  offeree,  —  the 
increased  or  diminished  spare  force  of  revolution,  which 
records  itself  in  the  greater  or  less  flow  of  the  tides,  and  in 
the  host  of  connected  phenomena. 

The  maxima  and  minima  of  the  tides  take  place  after  the 
new  and  full  moon,  and  after  the  quadratures.  If  the  cause 
of  the  increase  and  diminution  of  the  current  of  force  is  the 
oscillatory  motion  of  the  earth  in  her  orbit,  the  onward  move- 
ment of  the  vibration  would  continue  after  the  cause  had 
passed  its  maximum ;  the  motion  of  the  earth  would  go  on,  and 
its  greatest  aberration  would  be  some  two  or  three  days  after 
the  culminating  point  of  the  satellite  which  determined  the 
range  of  the  perturbation.  The  extreme  point  of  all  connected 
phenomena  thus  advances  beyond  the  exciting  cause.  In 
the  extreme  of  the  oscillation  of  the  surface  of  the  earth,  its 
opposite  expansions  and  contractions  stretch  beyond  the 
normal  hour.  In  the  triple  manifestation  of  the  flow  of  force 
by  the  barometer,  needle,  and  tension  of  vapor,  the  highest 
and  the  lowest  range  are  not  at  noon  and  midnight,  morning 
and  evening,  but  at  later  hours.  There  can  be  in  the  econ- 
omy of  nature  no  sudden  suspension  of  the  motion  of  large 
masses.  The  transfer  of  force  which  accelerates  or  retards 
is  a  gradual  process.  No  sphere  could  withstand  a  sudden 
change  in  the  force  which  moves  it ;  and  we  love  to  bring 
to  mind  the  ease  and  elasticity  of  the  motion  of  worlds,  free 
to  swerve  in  their  own  diameters  and  to  bend  in  their  orbits, 
yet  every  change  having  the  safeguard  of  limit,  the  compen- 
sation of  mutual  adjustments.  We  see  in  the  very  ellipti- 
cal form  of  the  orbits  of  the  planets  the  means  of  insuring 
this  ease  and  freedom  of  motion.  They  are  not  bound  in 


MECHANICAL    PHILOSOPHY.  247 

rigid  circles,  in  which,  by  the  fluctuations  and  transfers  of 
force,  the  time  of  rotation  and  revolution  would  be  increased 
or  diminished,  and  the  harmony  of  their  movements  be 
broken  up.  The  application  or  withdrawal  of  force  would, 
as  it  were,  break  a  circle,  and  the  planet  would  suddenly 
fall  to  or  from  the  centre  ;  while  the  ellipse  is  like  an  elastic 
spring.  The  elliptical  orbit  can  approach  nearer  to  or  recede 
farther  from  the  circle,  and  without  a  change  of  the  major 
axis  the  motion  can  be  quickened  or  retarded  in  different 
parts  of  the  orbit,  yet  the  period  of  the  circuit  be  forever 
the  same. 

But  to  return :  that  there  are  two  tidal  elevations  and 
two  tidal  depressions  of  the  ocean  waters,  is  known  from  the 
diurnal  ebb  and  flow  on  the  coast.  How  are  these  waves 
lifted  up  ?  In  what  manner  are  these  alternate  elevations 
and  depressions  of  the  great  deep  produced  ? 

We  will  suppose  that  there  is  not  an  alternate  rise  and 
fall,  but  that  the  elevation  is  permanent,  and  is  propagated 
round  the  world.  This  hypothesis  is  inadmissible  ;  for  the 
uplifted  waters  would  rush  along  with  a  speed  equal  to  the 
diurnal  motion  of  the  earth,  and  would  overwhelm  the  land. 
We  will  suppose  that  the  elevation  is  not  permanent,  but 
caused  by  a  horizontal  flow  of  water,  —  by  currents  heaping 
up  the  tidal  wave.  This  is  liable  to  the  same  objection,  and 
such  currents  could  not  be  formed  without  exhibiting  their 
intense  power.  Only  one  other  supposition  can  be  made,  — 
the  water  is  lifted  vertically,  gradually  raising  itself  up  from 
its  bed  and  then  again  subsiding  to  rest.  This  also  is  inad- 
missible ;  for,  were  the  waters  thus  raised  without  horizontal 
currents,  there  must  needs  be  a  vacuum  between  the  waters 
and  the  bottom  of  the  sea.  We  cannot  believe  that  to  form 


248  OUTLINES   OF  A    SYSTEM   OF 

the  tidal  wave  the  waters  flow  horizontally  round  the  earth, 
or  that  they  rise  vertically  from  their  resting  place. 

That  which  elevates  the  waters  also  elevates  the  earth  on 
which  they  rest.  It  is  the  enlargement  of  the  globe  at  equi- 
distant points,  and  its  contraction  at  the  intermediate  points, 
which  rounds  upward  and  curves  downward  the  surface  of 
the  ocean.  This  is  the  reason  why  no  elevation  is  noticed  in 
inland  seas  and  lakes,  and  why  the  tidal  wave  never  mani- 
fests itself  on  the  sea-coast,  the  perceived  phenomena  being 
simply  the  consequent  ebb  and  flow  of  the  surface  water ; 
for,  as  sea  and  land  rise  together,  there  is  no  gauge  to  mark 
the  expansion  and  contraction  of  the  globe.  Nor  does  the 
curved  surface  of  the  ocean  away  from  the  land  give  the 
surface  flow.  Like  minor  waves  rising  by  the  possession  of 
the  due  degree  of  force  for  the  level  to  which  they  ascend, 
the  waters  are  at  the  true  level  corresponding  to  their 
present  force.  The  comparatively  non-conducting  land  does 
not  give  out  the  required  force,  and  near  the  land  the  un- 
supported waters  establish  the  surface  flow,  and  the  more 
land-locked  the  waters  of  the  ocean,  as  in  bays  and  chan- 
nels, the  greater  is  this  flow.  In  the  Bay  of  Fundy  the  rise 
of  the  isolated  waters  is  more  than  sixty  feet,  while  the  tide  is 
hardly  perceptible  on  the  shores  of  the  broad  Pacific.  The 
condition  of  oscillation  is  that  the  fall  shall  furnish  the  force 
for  the  rise.  In  the  great  vibration  of  the  waters,  the  fall- 
ing must  transfer  to  the  rising  water  its  needed  support ;  if, 
therefore,  the  connection  be  in  part  cut  off,  —  if  there  inter- 
vene a  barrier,  —  the  force  for  support  at  the  higher  level 
may  not  be  furnished.  From  this  may  perhaps  come  the 
horizontal  flow.  We  present  the  idea  for  consideration,  as 
one  that  may  account  for  the  known  facts. 


MECHANICAL    PHILOSOPHY.        .  249 

The  tidal  wave  must  rise  at  every  half  rotation  of  the 
earth,  and  the  tidal  depression  must  take  place  at  the  inter- 
mediate equi-distant  hour.  The  time  cannot  change  ;  this 
oscillation,  being  determined  by  the  rotation  of  the  globe, 
must  coincide  with  the  time  of  rotation.  But  the  tidal  flow, 
though  caused  by  this  alternation,  is  an  independent  oscilla- 
tion. It  is  caused  by  it ;  but  its  movement  is  in  different 
time  and  of  a  different  nature.  One  is  a  horizontal  flow  of 
water  for  many  miles,  —  the  other,  a  vertical  rise  measured 
by  feet.  The  one  lags  behind  the  other.  They  may  be 
compared  to  two  unequal  pendulums,  the  longer  impelled 
into  vibration  by  the  motion  of  the  shorter,  and  their  lengths 
bearing  such  a  proportion  that  after  a  fixed  number  of  beats, 
the  motion  becomes  at  regularly  returning  periods  coinci- 
dent in  time. 

To  present  a  theory  of  the  tides  with  minute  exactness  of 
detail,  would  require  the  labor  of  years  exclusively  devoted 
to  the  subject.  We  give  the  thoughts  that  have  presented 
themselves  to  our  mind,  without  an  elaborate  analysis  of 
all  the  connected  parts.  We  feel  convinced  that  we  have 
pointed  in  the  direction  of  their  cause,  and  that  the  con- 
nection of  such  a  vast  array  of  phenomena  with  the  transfers 
of  force,  caused  by  the  unequal  orbits  of  the  rotation  and 
revolution  of  the  several  parts  of  the  earth,  proves  that  there 
is  the  spare  force  of  rotation  and  revolution  in  constant  diffu- 
sion, and  that  the  earth,  neither  within  her  circumference 
nor  in  her  orbit,  is  held  in  the  rigid  bonds  of  gravitation, 
but  that  an  incessant  and  periodical  oscillation  is  the  life  of 
the  universe. 

Before  we  leave  this  chapter,  which  we  have  devoted  to 
the  subject  of  the  tides,  we  would  once  again  recur  to  the 
opinion  we  expressed,  that  there  are  in  all  oscillatory  move- 


250  OUTLINES   OF  A   SYSTEM   OF 

ments  two  conditions  of  the  undulation,  —  one,  the  impulse 
or  cause  ;  the  other,  the  equipoise  or  balance,  to  receive 
the  impulse.  Thus,  in  the  oscillations  of  the  great  tidal 
waves,  we  have  for  the  impulse  the  transferable  force  of  the 
earth's  revolution  in  her  orbit,  passing  from  point  to  point 
in  self-adjusting  distribution,  according  as  successively  one 
hemisphere  may  require  more,  and  the  other  hemisphere 
less,  while  the  act  of  oscillation  is  the  reception  and  transfer 
by  the  crest  and  valley  of  the  wave  of  the  rotary  force  of 
the  world ;  the  one  receiving  the  more  as  it  rises,  the  other 
imparting  the  more  as  it  falls.  Here,  then,  is  a  meeting 
point  of  these  two  forces  of  rotation  and  revolution ;  here 
they  join  in  one  movement ;  here  is  the  place  of  inter- 
mingling, of  intercommunication,  so  that  the  excess  of  the 
one  can  supply  the  lack  of  the  other,  and  a  perfect  equi- 
poise be  established  for  the  preservation  of  the  harmony  of 
these  great  movements. 

Thus  is  presented  to  the  mind,  instead  of  two  isolated  in- 
dependent forces,  the  one  for  revolution,  the  other  for  rota- 
tion, one  majestic  power,  now  divided  according  to  the  need 
of  motion,  now  commingling  in  some  common  movement. 
Thus  harmonious  is  nature,  thus  perfect  in  action  is  the 
creating  thought  of  God,  —  a  complete  whole,  in  which  even 
-excess  and  defect,  if  they  can  occur,  most  perfectly  balance 
each  other. 

We  have  no  sympathy  with  theories  by  which  the  world 
is  whirled  about  "  with  the  dust  of  its  own  grinding," 
or  its  energy  is  impaired  by  the  friction  of  its  own 
action.  We  read  such  passages  as  the  one  we  now  quote 
with  feelings  of  revulsion,  though  it  is  not  unusual  language  : 
"  Though  we  cannot  by  any  stretch  of  the  imagination  em- 
brace the  period  of  the  duration  of  the  system,  the  conclu- 


MECHANICAL  PHILOSOPHY.  251 

sion  still  forces  itself  on  the  mind  that  at  last  it  must  end, 
that  one  by  one  the  planets,"  by  the  action  of  gravitation, 
"  must  be  lost  in  the  sun,  the  sun  itself  perhaps  be  merged 
in  other  suns,  to  contribute  by  the  immensity  of  its  attrac- 
tion to  the  destruction  of  other  systems  ;  that  such  will  be 
the  inevitable  effects  is  admitted ;  but  no  inhabitant  will 
witness  the  catastrophe,  for  long  before  that  event  our  race 
will  have  been  destroyed  by  the  heat  consequent  on  the 
reduction  of  the  orbit  of  the  earth." 

Distrust  all  theories  which  involve  the  gradual  construc- 
tion, or  the  gradual  wearing  out  of  the  universe.  It  caine 
when  God  willed,  perfect  at  the  very  first ;  it  will  continue 
without  sign  of  weakness  or  mark  of  decay  so  long  as  He 
may  determine,  unworn  and  unimpaired,  until  He  decrees 
its  end,  when  it  shall  have  fulfilled  His  august  design. 
Change,  apparent  to  us,  is  the  life-giving  stamp  of  per- 
petuity. 

"  The  world's  unwithered  countenance 
Is  bright  as  at  creation's  day." 

There  is  a  wide-spread  belief  that  one  of  the  planets  of 
the  solar  system  has  been  broken,  —  that  the  Asteroids  are 
the  fragments  of  that  shattered  globe.  This  idea  meets  us 
everywhere.  It  is  expressed  in  standard  books  on  astrono- 
my, and  in  the  rudhnental  treatises  designed  for  district 
schools.  What  are  the  facts  ?  How  did  this  idea  originate  ? 
Long  since,  in  the  days  of  Kepler,  it  was  observed  that  the 
space  between  Mars  and  Jupiter  was  too  extensive  to  be 
untenanted.  There  was  a  break  in  the  series  of  planets,  — 
the  proportional  distance  was  not  maintained.  One  planet 
was  wanted  to  give  uniformity  to  the  system,  —  to  perfect 
the  theory  of  relative  distances. 


252  OUTLINES,   ETC. 

On  the  discovery  of  the  first  Asteroids,  the  facts  could  be 
accommodated  to  the  asserted  law  of  distances,  by  the  sup- 
position that  these  small  planets  were  parts  of  the  one  planet 
which  should  have  occupied  the  space  between  Mars  and 
Jupiter,  —  that  by  some  internal  convulsion  this  planet  was 
rent  asunder,  or  broken  into  pieces  by  a  blow  from  some 
erratic  comet.  This  idea  of  a  God-deserted  world  left  to 
the  conflict  of  its  own  unrestrained  forces,  or  wrongly  placed 
so  as  to  be  in  the  way  of  some  other  sphere,  was  entertained 
for  no  other  reason  than  that  the  supposition  conformed  the 
system  to  Bode's  law  of  planetary  distances. 

We  would  not  venture  to  assert  that  worlds  may  not,  by 
omnipotent  power,  be  recreated  from  the  fragments  of  other 
worlds,  —  that  the  component  parts  of  one  sphere  may  not 
be  remodelled  into  other  spheres.  But  we  cannot,  merely 
to  make  good  a  mathematical  calculation,  entertain  the  idea 
of  a  broken  planet  with  the  angular  fragments  of  its  crust 
rounded  into  spheres  by  their  own  motion,  revolving  with 
orbits  arranged  and  places  assigned  by  the  action  of  their 
centripetal  and  centrifugal  forces.  We  need  higher  evi- 
dence than  Bode's  law.  We  regard  the  asteroidal  system, 
the  twelve  or  sixteen  worlds  revolving  in  their  eccentric  and 
beautifully  interlaced  orbits,  as  another  striking  and  won- 
derful exhibition  of  the  power  and  wisdom  of  Him  who 
formed  them,  —  this  variety  in  unity,  as  another  evidence  of 
design,  —  this  part  of  the  heavens,  as  declaring  afresh  the 
glory  of  God,  and  showing  forth  His  handiwork. 


CHAPTER    X. 


;*  IN    ORDER    TO    BIND    TOGETHER    FACTS,    THEORY    IS    REQUISITE    AS 
WELL  AS   OBSERVATION,  —  THE    CORD   AS   WELL  AS   THE   FAGOTS." 

Whewell. 

THE  trade-winds,  —  which  are  supposed  by  some  to  be  an 
aerial  tide,  caused  by  the  attraction  of  the  sun  and  moon,  — 
oceanic  currents,  and  some  connected  phenomena,  now 
claim  our  attention. 

In  a  former  chapter  we  expressed  the  belief  that  there  is 
a  general  law  which  governs  the  secondary  movement  of 
the  planets  as  well  as  their  primary  movement ;  that  is, 
that  there  is  a  normal  intensity  of  rotary  motion,  as  well 
as  of  the  motion  of  revolution,  belonging  to  every  sphere, 
and  that  the  one  is  in  a  fixed  ratio  to  the  other.  But  as, 
from  its  form,  the  intensity  of  rotation  decreases  from  the 
surface  of  a  globe  to  its  axis  of  motion,  the  law  which 
governs  this  movement  must  be  related  to  the  mean  velo- 
city, and  not  to  the  velocity  of  either  extreme,  —  to  the 
average  speed,  not  to  the  motions  of  either  the  equatorial 
or  polar  regions. 

From  this  consideration,  it  is  evident  that  while,  in  the 
earth,  for  instance,  there  exists  the  due  amount  of  rotary 
force,  this  force  is  unequally  distributed  through  its  mass. 
There  are  therefore  portions  which  have  a  greater,  and  those 
which  have  a  less  degree  of  force,  than  the  mean  force  belong- 
ing to  the  sphere.  From  the  tendency  of  force  to  diffuse 

22 


254  OUTLINES   OF  A   SYSTEM   OF 

itself  equally  through  every  mass  of  matter,  and  from  the 
law  that  force  is  transferred  from  matter  not  susceptible  of 
motion  by  it  to  matter  free  to  move,  it  follows,  as  force  is 
distributed  through  the  earth  according  to  the  capacity  for 
motion,  that  air  and  water,  to  the  extent  in  which  they  are 
free  to  move  independently  of  the  more  solid  parts  of  the 
earth,  will  have  at  the  poles  a  motion  greater  than  that  of 
the  earth,  and  that  these  elements  at  the  equator  will  have 
less  motion  than  the  earth. 

To  illustrate  these  ideas  :  Were  the  earth  a  perfect 
sphere,  the  mean  surface  velocity  of  rotation  would  be 
found  at  the  parallels  of  45°  north  and  south  latitude,  and, 
as  the  earth  is  shaped,  this  determination  is  sufficiently 
accurate  for  the  purpose  of  general  illustration.  From  this 
line  of  mean  velocity  of  surface  rotation,  towards  the  poles 
as  well  as  towards  the  equator,  the  rotary  force  exists  in 
varying  degrees,  according  to  the  capacity  for  motion  of  the 
different  parts  rotating  as  a  united  sphere.  But  the  force 
will  not  be  thus  distributed  to  that  matter,  which  at  the 
equatorial  or  polar  regions  is  not  necessarily  a  rigorously 
connected  part  of  the  earth,  and  which  may  have  some  ca- 
pacity for  motion  independent  of  the  motion  of  the  sphere. 
To  the  degree,  therefore,  in  which  air  and  water  have  the 
power  of  independent  motion,  this  motion  will  be  found  to 
be  related  in  its  action  to  the  mean  surface  velocity. 

The  atmosphere  has  this  freedom  of  independent  motion. 
In  its  movement,  therefore,  it  will  be  found  that  the  mean 
velocity  of  rotation, — that  with  which  the  surface  of  the  earth 
moves  at  45°  latitude, — will  be  the  governing  principle  of  its 
independent  motion.  It  will  limit  its  eccentricity.  The 
winds,  of  course  modified  by  other  laws,  will,  as  a  general 
principle,  be  related  to  this  mean  of  rotation,  and  a  reference 


MECHANICAL    PHILOSOPHY.  255 

to  this  fact  will  be  found  to  dissipate  some  of  the  mysteries 
of  the  movements  of  this  free  element.  The  atmosphere  at 
the  north  polar  regions  and  the  adjoining  parts  of  the  tem- 
perate zone  may  have  a  force  of  motion  more  intense  than  the 
the  rotary  force  of  those-portions  of  the  earth.  It  will  there- 
fore move  southward  to  increase  the  orbit  of  rotation,  and 
eastward  because  it  moves  faster  than  the  earth.  Hence  the 
prevalence  of  northwest  winds  in  those  regions.  As  we  pro- 
ceed southward  through  the  mean  of  rotation,  there  is  found 
a  great  belt  of  variable  winds.  "  What,"  says  Mr.  Guyot, 
in  reference  to  these  regions,  "  is  more  fickle  and  capricious 
than  the  winds  ?  They  are  symbols  of  changeableness  itself." 
At  the  equatorial  regions,  the  atmosphere  has  less  force  of 
rotation  than  the  surface  of  the  earth  on  which  it  rests  ;  of 
course  it  has  an  apparent  motion  westward,  from  moving 
more  slowly  than  the  earth.  This  wind  also  blows  from  the 
centre  northward  and  southward,  thereby  narrowing  its 
orbit  of  rotation,  —  the  converse  of  the  action  of  the  winds 
from  the  poles,  which  move  southward  and  northward  to 
widen  the  orbit  of  rotation.  The  easterly  trade  winds,  by 
the  clouds  and  vapor  which  they  transport,  may  present  the 
aspect  of  two  zones,  which  seen  from  the  moon  might  appear 
like  the  belts  of  Jupiter,  which  planet,  from  its  immense 
diameter,  and  the  consequently  great  velocity  of  surface 
rotation,  would  most  distinctly  present  the  zones  of  retarded 
and  accelerated  atmospheric  motion. 

We  notice  in  the  Annual  of  Science  that  Mr.  Babinet 
refers  to  retarded  and  accelerated  rotation  as  the  cause  of 
oceanic  currents,  believing  "  that  the  waters  which  flow 
from  the  equator  have  an  inclination  to  advance  before  the 
motion  of  the  earth,  whilst  those  which  come  from  the  poles 
have  a  tendency  to  remain  behind  the  motion."  But  we 


256  OUTLINES    OF   A    SYSTEM    OF 

apprehend  that  the  reverse  is  the  case.  The  waters  follow 
the  laws  of  the  atmosphere,  and  in  their  respective  motions 
there  is  that  resemblance  which  indicates  the  same  general 
law.  There  is  the  great  westerly  current  of  the  equatorial 
regions  corresponding  to  the  trade  winds.  This  extensive 
current  is  deflected  northward  or  southward,  when  it 
strikes  the  eastern  shores  of  the  continents,  and  thus  its 
waters  narrow  their  orbit  of  rotation  by  advancing  towards 
the  poles.  The  currents  flowing  from  the  polar  regions 
widen  their  orbit  by  their  advance  towards  the  equator. 
At  the  point  of  equilibrium  of  rotary  force,  about  the 
parallels  of  45°  north  and  south,  all  the  oceanic  currents 
are  turned  to  the  eastward.  Thus,  in  this  general  eastward 
movement  is  found  the  compensation  for  the  great  westerly 
current  of  the  tropics,  and  the  equilibrium  of  the  waters  is 
preserved. 

It  has  been  supposed  that  the  Gulf  Stream,  which  is  a 
branch  of  the  great  westerly  current  arrested  by  land  and 
turned  northward  along  the  coast  of  the  United  States,  is 
deflected  to  the  eastward  in  latitude  45°  by  the  Banks,  which 
extends  across  the  Atlantic  Ocean  in  about  this  parallel. 
We  are  inclined  to  the  opinion  that  the  same  cause  which 
turns  the  current  also  forms  the  Banks.*  This  deflection  is 
not  local  and  accidental.  The  current  flowing  by  the  east- 
ern shores  of  Asia  bends  to  the  eastward  at  the  same  par- 

*  It  is  said  that  soundings  extend  from  the  Newfoundland  Banks  across 
the  Atlantic  Ocean.  We  are  also  informed  by  an  experienced  navigator, 
that  in  the  summer  season  the  Gulf  Stream  flows  farther  north  before  its 
bend  to  the  eastward  than  it  does  in  the  winter,  thus  following  the  sun  as 
do  the  trade-winds,  —  these  phenomena  being  related  in  their  changes  to 
the  changing  angle  of  rotation  and  revolution,  the  extreme  points  of  the 
earth  in  their  revolution  following  the  direction  of  the  sun  as  the  centre  of 
revolution 


MECHANICAL  PHILOSOPHY.  257 

allel ;  in  the  same  degree  of  south  latitude,  a  polar  current 
flowing  northward  bends  to  the  eastward  off  the  Cape  of 
Good  Hope,  while  inshore  close  to  the  Cape,  there  is 
a  westerly  current,  these  opposite  currents  running  side 
by  side.  The  parallels  of  45°  are  the  dividing  lines  ;  cur- 
rents in  lower  latitudes  flow  westerly,  in  higher  latitudes 
flow  north  and  south  with  an  easterly  tendency,  until  they 
reach  this  point  when  they  are  turned  eastward,  the  waters 
on  one  side  of  the  equilibrium  of  force  having  a  greater, 
and  on  the  other  side  a  less  intenseness  of  velocity,  than  the 
solid  earth.  The  deviations  from  this  general  law  are 
caused  by  the  position  of  the  coasts  against  which  the  waters 
impinge.  In  the  map  of  currents  presented  in  Guyot's 
"  Earth  and  Man,"  every  arrow  showing  their  direction 
conforms  to  this  statement.  The  moving  elements,  air  and 
water,  in  the  polar  regions  move  with  greater,  in  the  equa- 
torial regions  with  less,  than  the  mean  force  of  the  rotation 
of  the  earth.  Why,  then,  trace  the  cause  of  the  trade 
winds  to  the  rarefaction  of  the  atmosphere,  caused  by  the 
more  intense  action  of  the  sun's  rays  within  the  tropics  ? 
Why  speak  of  the  attraction  of  the  sun  and  moon  as  caus- 
ing aerial  tides,  or  oceanic  currents,  or  tidal  waves  ?  The 
cause  of  these  phenomena  will  be  found  on  the  earth,  not  in 
the  skies,  —  in  the  changing  force  of  the  motion  of  our  own 
planet,  not  in  the  attractive  power  of  other  spheres. 

Geology  may  find,  in  a  reference  to  the  parallels  of  mean 
rotary  velocity,  some  help  in  the  investigation  of  the  struc- 
tural changes  of  the  earth.  The  erratic  drift  of  boulders  and 
diluvium  is  spread  over  the  frigid  zone  and  over  the  north- 
erly parts  of  the  temperate  zone  of  the  northern  hemisphere. 
This  dispersion  of  drift,  we  believe,  was  simultaneous.  The 

22* 


258  OUTLINES   OF  A   SYSTEM   OF 

torrent  rushed  from  the  polar  region  southward,  with  an 
inclination  eastward.  Its  southerly  bounds  are  about  the 
parallel  of  45°.  Again  ;  the  range  of  the  drift  of  icebergs 
seems  to  be  determined  by  their  equilibrium  parallels.  The 
mean  temperature  of  the  earth  at  the  poles  is  said  to  be 
about  10°  of  Fahrenheit;  and  about  two  or  three  degrees 
below  zero  at  the  two  poles  of  maximum  cold,  twelve  degrees 
distant  from  the  poles  of  the  earth's  axis.  The  Arctic  and 
Antarctic  Oceans  are  frozen  to  a  very  great  depth,  and 
"  during  eight  months  of  the  year  a  continuous  body  of  ice 
extends  round  the  poles  of  maximum  cold,  occupying  a  sort 
of  elliptical  area  of  above  four  thousand  miles  of  diameter." 
Icebergs  are  detached  from  the  margin  of  this  frozen  zone 
at  certain  seasons.  By  a  beautiful  provision  of  nature,  ice 
cooled  to  a  certain  degree  changes  its  character,  and  from 
being  a  non-conductor  becomes  a  conductor  of  force ;  at 
one  time,  as  if  it  were  a  mantle  spread  over  the  earth  and 
sea,  it  confines  the  heat  until  the  extreme  is  beyond  the 
limit  which  nature  has  assigned  ;  it  then  is  no  longer  a  bar- 
rier to  the  required  adjustment,  —  and  perhaps  by  this  very 
means,  some  transfer  of  force  rends  the  masses  of  icebergs 
from  the  parent  bed  of  ice,  and  urged  by  the  present  force 
they  move  slowly  but  strongly  towards  the  south  or  north, 
undisturbed  in  their  advance  by  storm  or  current,  until  by 
the  widened  orbit  of  rotation  the  force  which  impelled  them 
from  the  poles  is  absorbed.  Icebergs  have  been  observed 
thirteen  miles  in  length,  with  perpendicular  sides  rising  at 
least  one  hundred  feet  above  the  surface  of  the  sea ;  but 
they  are  found  of  all  sizes  and  shapes  drifting  from  the 
frozen  oceans.  This  drift  of  ice  is  arrested  mainly  at  about 
the  parallels  of  45°,  though  solitary  masses  may  occasionally 
stray  farther  from  the  poles.  The  icebergs  of  the  northern 


MECHANICAL  PHILOSOPHY.  259 

Atlantic,  it  is  well  known,  collect  at  the  Newfoundland 
Banks  as  their  resting  place  ;  for  there  the  mean  of  rotation 
is  obtained. 

We  notice  the  same  limit  to  the  drift  on  the  land, —  to  the 
transportation  of  diluvium  and  boulders  from  the  north. 
The  course  of  this  mineral  or  earthy  flow  was  southeasterly. 
Its  path  is  written  down  in  grooves  and  striae,  or  diluvial 
scratches,  and  by  the  smoothing  of  the  northern  sides  of  the 
mountains.  This  current  also  arrested  its  flow  when  the 
impelling  force  was  reabsorbed  in  rotation  by  the  extension 
of  its  diurnal  orbit.  But  the  flow  of  earth  and  stone  was 
not  like  the  slow  movements  of  the  icebergs ;  by  a  sudden 
rush,  as  it  were,  the  mountain  masses  fell  from  the  north. 
The  one  is  from  the  every-day  action  of  force,  —  the  other 
came  from  a  readjustment  of  the  earth's  surface  when  it  took 
the  form  which  fitted  it  for  the  home  of  man.  The  limit  of 
the  drift  is,  however,  the  mean  parallel  of  latitude, — the 
boulders  and  diluvium  in  northern  Europe  and  northern 
America  being  confined  to  the  Arctic  zone,  and  to  the 
northern  part  of  the  temperate  zone.  There  is  no  easterly 
or  westerly  drift,  and  none  beyond  the  parallels  of  mean 
latitude,  or  none  of  great  extent  arising  from  any  widely 
acting  cause. 

The  diluvial  scratches  or  striae  marking  the  track  of  the 
erratics  from  the  north,  are  straight  as  a  mathematical  line. 
They  are  found  on  the  plains,  on  the  northerly  side,  and 
occasionally  on  the  south  side  of  mountains.  By  whatever 
force  they  were  moved,  their  course  was  not  obstructed  by 
the  inequalities  over  which  they  passed.  They  flowed  on 
as  if  without  weight,  —  now  lightly,  now  heavily  touching 
the  surface  of  the  earth,  ascending  or  descending  as  more 
or  less  upborne  by  the  impelling  force. 


OUTLINES    OF   A    SYSTEM    OF 

We  believe  that  these  mountain  masses  moved  with  in- 
tense velocity, because  the  striae  were  so  evenly  grooved.  No 
current  of  water,  nor  iceberg  floating  in  the  current,  nor 
slide  or  glacier,  could,  from  known  causes  move  with  sufficient 
velocity  to  form  these  grooves.  There  would  be  irregulari- 
ties of  motion,  depressions,  gyrations.  There  is  another  proof 
of  the  intense  velocity  of  the  motion  of  this  flood  of  rocks. 
The  edges  of  the  engraving  rock,  the  angular  points  which 
made  the  record,  did  not  wear  down  or  become  blunted. 
The  only  wear  was  on  the  tablet  which  received  the  im- 
pression. The  effect  of  great  velocity  is  to  preserve  the 
cohesion  of  the  moving  body  or  instrument.  A  tallow 
candle,  soft  as  it  is,  when  discharged  from  a  gun  will  pierce 
through  a  pine  board.  Thus,  by  intense  velocity  alone  could 
the  sharp  angle  of  the  rock  making  the  impression  be  pre- 
served. A  slow  motion  of  the  mass  would  have  worn  the 
engraving,  as  well  as  worn  into  the  engraved  rock,  and 
there  could  not  have  been  an  equal  and  even  groove  made 
for  any  considerable  distance.  It  has  been  remarked,  that 
the  striae  might  have  been  caused  by  small  stones,  pebbles, 
or  sand,  between  the  drifting  boulders  and  the  rocks  over 
which  they  moved.  But  such  intervening  substances  would 
have  been  crushed  by  the  weight  and  friction.  Smoothing 
or  polishing  to  some  extent  might  have  been  produced  by 
this  means,  but  not  the  straight  furrow. 

The  vortex  moulds  (pot  holes)  to  which  we  have  before 
referred,  are  circular  cavities  formed  in  the  solid  rock. 
These  generally  contain  a  rounded  stone  or  stones.  On  the 
shores  of  Lake  Superior  are  many  of  these  cavities,  and  we 
are  told  that  "  a  stone  in  one  of  these  might  have  weighed 
fifty  pounds.  Some  of  the  holes  were  three  or  four  feet 
deep,  and  as  many  in  diameter ;  some  of  them  formed 


MECHANICAL    PHILOSOPHY.  261 

steps,  the  stone  having  worn  down  at  one  side  of  the  hole, 
and  worked  on  horizontally  awhile,  and  then  downwards 


again." 


It  has  been  surmised  that  these  holes  were  worn  into  the 
rock  by  the  action  of  water  on  stones  lodged  in  its  crevices. 
How  could  waves  or  running  water  make  stationary  whirl- 
pools sufficient  to  whirl  stones  weighing  fifty  pounds  penned 
up  in  a  narrow  crevice  ?  Yet  only  a  swift  rotary  motion 
of  the  encaged  stones  could  have  worn  these  circular  holes. 

The  motion  required  to  produce  these  smoothly  rounded 
excavations  could  hardly  be  induced  by  the  action  of  water. 
The  stones  which  formed  them  were  probably  arrested  frag- 
ments of  the  rushing  flood  of  rocks.  Their  onward  motion 
being  suspended,  they  would  revolve  with  the  same  force 
which  before  impelled  them  in  a  right  line.  They  would 
act  as  the  arrested  water  of  a  current  which  exhausts  its 
force  in  the  whirlpool ;  and  the  existence  of  such  excava- 
tions seems  to  prove  the  intense  velocity  of  the  erratic  drift. 

We  refer  the  period  of  the  drift  to  the  time  of  the  great 
change  in  the  earth,  which  under  the  Providence  of  God 
gave  to  it  its  present  form.  The  moving  mountains  acted 
upon  by  a  force  more  than  sufficient  for  rotation  at  their 
position  rushed  southward,  with  an  easterly  inclination 
widening  their  orbit,  and  moving  with  great  velocity  until 
they  arrived  at  the  place  of  rest. 

If  this  hypothesis  be  unsound,  we  believe  that  no  theory, 
which  does  not  refer  the  rush  to  a  current  of  the  most  intense 
velocity,  can  explain  the  erratic  drift.  The  respect  we  en- 
tertain for  those  who  seek  to  account  for  the  facts  of  the 
case  from  natural  every-day  causes,  leads  to  hesitation,  and 
an  analogous  action  on  a  smaller  scale  would  confirm  the 
doubt ;  but  the  record  on  the  mountain-sides,  the  characters 


262  OUTLINES   OF   A   SYSTEM   OF 

uneffaced  by  time  impressed  on  the  granite  tablet,  tell  us  of 
a  power  no  longer  in  operation,  the  action  of  which  was 
never  observed  by  man. 

Meteorology,  if  it  may  be  allowed  the  name  of  science, 
is  a  science  of  facts  only.  The  meteorologist  neither  fore- 
tells the  weather,  nor  explains  its  phenomena.  He  sits, 
patiently  musing  over  storm  and  calm,  tornado  and  zephyr, 
fog  and  sunshine,  the  arctic  cold  and  the  torrid  heat,  look- 
ing anon  at  the  weathercock  and  the  barometer,  diligent  in 
recording  variations,  in  a  note-book  already  full  of  facts, 
without  a  principle  for  their  arrangement  or  explanation, — 
waiting  for  light  to  shine  forth  from  his  recorded  observa- 
tions upon  the  vicissitudes  of  the  weather. 

Yet  there  is  nothing  out  of  rule,  beyond  law,  in  these 
apparently  capricious  changes.  There  is  nothing  in  this 
world  of  ours  without  a  cause.  The  vane  never  turns  but 
by  the  operation  of  law  altering  the  direction  of  the  wind : 
nor  are  the  laws  which  govern  the  gale  and  the  storm  so 
complicated  and  mysterious  that  there  is  no  hope  that  the 
mind  may  comprehend  them.  In  olden  times  the  heavenly 
bodies  presented  to  the  observer  nothing  but  involved,  con- 
fused, entangled  movements  ;  yet  the  harmonious  motion  of 
the  spheres  now  ascertained  gives  to  the  astronomer  his 
deepest  impression  of  the  simple  majesty  of  nature.  If,  a  cen- 
tury ago,  it  had  been  asserted  that  the  time  would  come 
when  an  almost  instantaneous  communication  of  thought 
could  be  made  to  a  friend  a  thousand  miles  off,  and  that 
ideas  would  rush  across  continents  with  the  speed  of  light- 
ning, the  expression  of  this  now  established  fact  would  have 
been  deemed  as  wild  and  chimerical  as  it  may  seem  at  present 
to  say  that  future  ages  will  so  comprehend  the  laws  of  the 


MECHANICAL    PHILOSOPHY.  263 

elements,  that  to  a  very  great  and  practically  important 
extent,  the  common  weather  will  be  predicted.  Compare 
any  one  science  as  it  now  is  with  its  condition  centuries 
ago,  and  we  hardly  dare  to  limit  its  possible  advance  ; 
for  its  progress  is  with  accumulative  velocity;  discovery 
does  not  exhaust  the  field  ;  every  instance  of  successful 
inquiry  gives  a  vantage  ground  for  greater  results.  Why 
should  we  doubt  ?  "  Even  .ZEolus  reigns  by  law,"  and 
there  is  a  control  over  the  wildest  elements.  The  law  which 
directs  and  restrains  has  not  been  promulgated,  yet  we  wit- 
ness the  exercise  of  this  control.  In  every  truce  which 
terminates  the  struggle  of  the  elements  we  recognize, 
though  we  may  not  understand,  the  agency  which  effects  it. 
We  quote  the  following  from  an  article  in  the  North 
British  Review :  "  For  weeks  and  months  the  hourly  varia- 
tions [of  heat]  are  of  the  most  capricious  and  irregular 
character ;  the  thermometer  being  sometimes  stationary 
for  a  day ;  sometimes  highest  at  midnight,  and  lowest  at 
noon.  When  we  combine  however  the  three  hundred  and 
sixty-five  observations  at  each  hour,  we  find  these  hourly 
means  are  the  ordinates  of  a  curve  of  beautiful  regularity, 
each  of  the  four  branches  of  which  do  not  differ  more  than 
a  quarter  of  a  degree  of  Fahrenheit  from  parabolas.  The 
varying  temperature  of  a  day,  therefore,  with  all  its 
starts  and  irregularities,  is  controlled  by  a  law  as  precise 
and  unerring  as  that  which  regulates  the  planetary  motions. 
But  the  other  agencies  of  the  atmosphere  have  not  been 
subjected  to  law.  The  wind  and  the  rain,  the  hail  and  the 
snow,  the  storm  and  the  tempest,  seem  to  have  a  will  of 
their  own,  and  to  triumph  in  mockery  over  the  person  and 
property  of  man  ;  yet  lawless  as  they  appear,  we  shall  some 
time  or  other  discover  their  haunts  and  disclose  their 


OUTLINES   OF   A   SYSTEM   OF 

secrets,  even  though  we  may  never  succeed  in  disarming 
their  fury  and  reducing  their  power.  Even  the  hurricane 
and  tornado  must  yet  submit  to  intellectual  control,  nor 
shall  the  lightnings  of  heaven  escape  the  analysis  of  genius. 
.  .  .  The  time  will  come  when  the  electric  flash  will  be  pre- 
dicted with  as  much  certainty  as  the  occultation  of  a  star, 
or  the  emersion  of  a  satellite  from  the  shadow  of  its  planet." 

If  in  any  department  of  inquiry  there  be  not  an  even  ad- 
vance, if  any  science  lags  behind  the  others,  there  is  great 
reason  to  suspect  that  there  is  some  radical  defect  in  the 
foundation-theories  on  which  that  science  is  based  ;  its  culti- 
vators should  therefore  go  back  and  reexamine  the  first 
principles  on  which  it  rests ;  these  readjusted  with  accu- 
racy, they  may  be  able  to  hold  even  way  with  their  associ- 
ated laborers  in  the  much  divided  field  of  inquiry. 

Upon  a  reexamination  of  first  principles,  it  may  be  found 
that  the  defect  to  be  remedied  in  the  department  of  mete- 
orology is  a  mistaken  idea  of  the  extent  of  the  influence  of 
the  sun,  both  in  relation  to  his  attraction  and  to  the  heat 
which  emanates  from  him.  It  may  be  that  the  meteorolo- 
gist goes  too  far  from  the  field  of  action,  for  the  cause  of - 
action,  —  that  he  traces  too  much  to  foreign  influence,  too 
little  to  domestic  changes. 

We  quote  from  Sir  John  Herschell  a  description  of  the 
supposed  immense  range  of  the  sun's  influence.  "  The 
sun's  rays  are  the  ultimate  source  of  almost  every  motion 
which  takes  place  on  the  surface  of  the  globe.  By  its  heat 
are  produced  all  winds,  and  the  disturbances  which  result 
in  the  changes  of  the  electric  condition  of  the  atmosphere. 
By  these  rays  the  waters  of  the  sea  are  made  to  circulate 
in  vapor.  By  them  are  produced  all  the  disturbances  of 
the  chemical  equilibrium. "  And  the  paragraph  concludes 


MECHANICAL  PHILOSOPHY.  265 

by  assigning  the  phenomena  of  volcanic  action,  indirectly, 
to  the  rays  of  the  sun.  Even  more  sweepingly  are  all 
the  changes  of  weather  made  dependent  on  solar  influence. 
We  can  hardly  call  to  mind  a  single  fact  in  this  department 
that  is  not  explained  by  the  vacua  of  the  atmosphere,  —  by 
the  unequal  rarefaction  of  the  air,  produced  by  varying 
temperatures. 

The  winds  have  but  this  one  general  cause  assigned  to 
them  ;  and  yet,  if  there  are  as  great  inequalities  of  density 
in  the  atmosphere  as  are  supposed  to  exist,  it  does  not 
clearly  appear  how  these  could  create  the  winds,  with  their 
intensity  of  force,  long  duration,  and  extensive  range  of 
motion.  An  effect  must  be,  in  some  degree  at  least,  com- 
mensurate with  its  cause.  Motion  cannot  produce  or  pro- 
long itself  without  cause.  To  fill  vacua,  —  to  supply  addi- 
tional air  for  the  restoration  of  equilibrium  to  the  rarefied 
parts  of  the  atmosphere,  would  not  require  the  rush  of  the 
colder  air  for  months,  for  weeks,  for  days,  or  even  for  hours. 
The  repairing  and  equalizing  process,  as  the  winds  now  blow, 
would  cause  wider  breaches  of  continuity  than  are  repaired, 
—  would  create  more  void  places  than  are  filled.  This 
would  undoubtedly  be  the  case  when  the  horizontal  currents 
of  wind  are  greater  than  the  upward-flowing  current  of 
heated  air,  which  is  supposed  to  cause  the  wind.  Vacua 
are  filled,  and  the  equilibrium  of  the  density  of  the  atmo- 
sphere is  preserved,  by  the  elasticity  of  the  air.  This  acts, 
as  it  were  at  once,  almost  instantaneously ;  for  the  action 
of  elasticity  is  as  rapid  as  the  propagation  of  sound,  while 
gradually  heated  air  ascends  slowly,  its  place  being  sup- 
plied as  slowly.  It  can  never  create  the  intense  motion  of 
a  wind. 

The   colder  air  does  not  rush  toward  the  heated   air. 

23 


266  OUTLINES    OF   A   SYSTEM   OF 

Did  it  so  rush,  there  would  be  established  a  violent  wind, 
regular  and  unintermitting,  from  the  poles  to  the  equator  ; 
there  would  be  no  wind,  as  there  often  is,  speeding  from  the 
sunny  plains  of  the  south,  over  snow-clad  mountains,  toward 
the  region  of  perpetual  ice ;  the  trade  winds  would  not 
gently  flow,  spreading  themselves  toward  the  colder  north 
and  south  ;  nor  would  the  winds  of  the  frigid  zones  incline 
to  the  eastward.  It  is  true,  that  there  is  a  draft  of  air  to 
supply  combustion,  and  that,  whenever  heated  air  ascends, 
other  air  will  move  to  maintain  the  equilibrium.  The  com- 
parative density  of  the  air,  however,  cannot  account  for  the 
geographical  or  periodic  winds,  or  for  local  occasional 
storms.  It  cannot  explain  either  the  direction,  intensity,  or 
duration  of  the  wind.  Take,  for  an  instance,  the  circular 
motion  of  a  tornado  ;  how  can  this  movement  be'  induced  by 
a  vacuum,  or  how  can  it  restore  the  equilibrium  of  the 
atmosphere  ? 

The  idea  has  been  recently  entertained  by  scientific  men, 
that  the  trade  winds  arise  from  retarded  rotation.  It  is 
evident  that  the  same  cause  inclines  them  northward  or 
southward,  as,  by  thus  narrowing  the  orbit  of  rotation,  the 
equilibrium  of  motion  is  restored,  since  the  degree  of  present 
force  determines  the  orbit.  Thus  the  winds  from  the  frigid 
zones  flow  to  the  east,  moving  with  greater  velocity  than  the 
earth,  and  southwardly  or  northwardly  to  widen  the  circuit. 
Thus  the  degree  of  force  possessed  by  air  compared  with 
the  velocity  of  rotation  of  the  part  of  the  earth  over  which 
it  moves,  is  not  the  cause  of  the  east  and  west  winds  only, 
but  it  also  determines  the  direction  of  the  north  and  south 
winds.  The  inequality  of  force,  which  thus  gives  direction 
and  intensity  to  the  permanent  geographical  winds,  can  be 
traced  directly  to  the  differing  degrees  of  rotary  velocity 


MECHANICAL   PHILOSOPHY.  267 

of  different  parts  of  the  globe  ;  and  we  hope  to  be  success- 
ful in  tracing  the  inequality  which  gives  rise  to  the  variable 
and  occasional  winds. 

The  land  and  sea  breezes  alternating  with  day  and  night, 
are  frequently  cited  as  proof  that  the  varying  density  of  the 
air,  caused  by  differences  of  temperature,  determines  the 
direction  of  the  wind.  We  think  that  this  alternation  is  an 
illustration  of  the  views  which  we  present.  By  night  a 
greater  force  of  revolution  is  required,  by  day  a  less,  as 
the  part  of  the  earth  is  turned  from  or  towards  the  centre 
of  revolution.  The  regular  land  and  sea  breezes  are  most 
uniform  and  most  active  between  the  tropics,  where  day  and 
night  make  the  greatest  difference  in  the  orbit  of  revo- 
lution. These  changes  of  the  orbit  are  accompanied  by 
a  transfer  6f  force,  and,  of  course,  from  the  different  con- 
ducting powers  of  land  and  water  land  and  sea  breezes 
would  ensue. 

The  monsoons  are  periodic  winds,  which  in  some  regions 
blow  regularly  for  a  part  of  the  year  from  the  sea  land- 
ward, and  at  the  opposite  season  blow  from  the  land  toward 
the  sea.  In  the  regions  where  they  occur,  for  a  part  of  the 
year  the  meridian  sun  is  vertical  over  the  land,  and  for  a  part 
of  the  year  it  is  vertical  over  the  water.  This  is  the  con- 
dition of  these  periodical  alternations.  The  changing  posi- 
tion of  the  sun  indicates  that  the  earth's  axis  of  rotation  has 
changed  its  position  in  relation  to  the  centre  of  her  orbit. 
Of  course  the  angle  which  rotation  makes  with  revolution 
has  also  changed,  and,  where  monsoons  occur,  the  extremes 
of  revolution  periodically  pass  from  the  ocean  to  the  land, 
and  from  the  land  to  the  ocean.  The  change  of  the  position 
of  the  sun,  north  and  south  of  the  equator,  causes,  or 
rather,  denotes  the  change  of  the  flow  of  the  spare  force  of 


268  OUTLINES    OF   A    SYSTEM    OF 

revolution  which  moves  the  elements.  This  determines  the 
monsoons.  The  trade  winds  also,  in  some  degree,  follow 
the  course  of  the  sun  ;  in  our  latitudes  the  northwest  winds 
are  most  frequent  and  violent  in  the  winter  season  ;  the 
Gulf  Stream  in  summer  runs  further  north  before  it  bends 
to  the  eastward.  All  the  phenomena  thus  "  following  the 
sun,"  and  supposed  to  result  from  the  influence  of  his  rajs, 
and  the  consequent  inequalities  of  temperature,  can  thus  be 
traced  to  the  changes  of  relative  motion  of  different  portions 
of  the  globe,  which  alter  the  direction  of  the  currents  of 
force,  and  consequently  of  the  moving  elements,  air  and 
water.  The  position  of  the  sun  indicates  these  changes, 
but  neither  his  comparative  distance,  nor  the  comparative 
directness  or  obliquity  of  his  rays  produces  them.  As  the 
hands  of  a  clock  indicate  his  position,  so  does  his  position 
indicate  the  changes  of  the  motion  of  the  earth,  and  the 
changing  orbits  of  revolution  and  rotation  of  the  several 
parts  of  the  globe.  From  these  changes,  and  from  the  con- 
sequent changes  of  the  flow  of  force,  come  the  movements 
of  the  elements  which  give  us  the  variations  of  meteoro- 
logical phenomena. 

We  are  fully  aware  that  we  have  advanced  many  princi- 
ples, which  contradict  the  opinions  of  those  who  have  devoted 
themselves  to  the  examination  of  these  subjects.  In  meteo- 
rological science,  however,  we  do  not  feel  that  we  are  in  the 
opposition.  It  is  confessedly  an  open  field  of  investigation. 
There  is  little  or  nothing  definitely  settled,  and,  if  new 
theories  afford  any  clew  to  explanation,  this  result  may 
strengthen  these  theories  as  applied  to  subjects,  which  are 
generally  believed  to  be  well  explained  by  the  theory  of 
universal  gravitation. 

A   question  has  been  recently  proposed  from   a   high 


MECHANICAL   PHILOSOPHY.  269 

source,  "  whether  the  gush  of  rain  which  usually  follows 
the  detonation  of  a  thunder  storm  is  the  effect  or  the  cause 
of  the  electric  flash."  Should  there  not  be  principles  com- 
petent to  answer  such  inquiries,  or  rather  principles,  so 
thoroughly  settled,  so  accurately  determined,  as  forever  to 
prevent  such  questions  from  being  asked  by  scientific  men  ? 
This  is,  however,  but  one  of  the  many  points  on  which  no- 
thing is  distinctly  known.  What  creates  the  progressive  in- 
crease of  heat  from  the  arctic  to  the  torrid  zones  ?  Can  the 
comparative  obliquity  of  the  sun's  rays  give  a  full  and  satis- 
factory explanation  ?  Is  there  not  a  source  of  heat  in  the 
earth,  independent  of  the  rays  of  the  sun  ?  What  is  the 
cause  of  the  varying  degrees  of  humidity  in  the  atmo- 
sphere ?  Why  does  water  change  to  vapor  more  rapidly  at 
one  time  than  at  another  ?  Why  do  the  vapor  wreaths  now 
hang  over  the  surface  of  the  earth,  and  now  float  aloft 
as  clouds  ?  Whence  the  cirrus,  half-illuminated  clouds  ? 
Why  are  the  magnetic  poles  the  poles  of  maximum  cold  ? 
Why  do  the  curves  of  equal  temperature  have  for  their 
poles  th»e  poles  of  revolution  ?  All  these  phenomena  are 
surely  not  caused  by  the  inequality  of  the  sun's  rays,  their 
varying  obliquity,  and  the  consequently  irregular  density  of 
the  atmosphere. 

In  the  last  chapter  we  alluded  to  the  many  provisions, 
creating  the  transfer  of  force,  from  which  proceed  the  life- 
giving  alternations  of  the  world.  One  of  these  provisions 
was  the  diameter  considered  in  its  proportion  to  the  orbit 
of  revolution,  and  another,  the  velocity  of  rotation.  In  our 
planet,  the  greatest  diameter, — giving  the  widest  extreme  of 
the  differing  orbit  of  revolution  of  its  opposite  parts,  and 
the  most  intense  rotation,  —  is  between  the  tropics,  —  at  the 
equator.  In  that  region  consequently  will  occur  the  greatest 
23* 


270  OUTLINES   OF   A   SYSTEM   OF 

and  most  rapid  transfers  of  force.  Accordingly,  we  find  this 
indicated,  not  only  by  the  needle  and  barometer  shewing  even 
the  hourly  variations  of  the  strength  of  the  flow,  but  by  the 
greatest  and  most  sudden  alternations  of  all  meteorological 
phenomena.  There  are  the  most  active  volcanoes,  the  most 
frequent  convulsions  of  the  earth  and  disturbances  of  the 
electrical  condition  of  the  atmosphere,  and  the  most  violent 
hurricanes.  For  one  instance,  at  certain  seasons,  in  some 
places  between  the  tropics,  almost  every  day,  some  four  hours 
after  the  sun  has  attained  the  meridian,  there  is  a  thunder 
storm,  while  so  rare  is  this  occurrence  in  the  northern 
regions,  that  a  traveller  mentions  as  a  fact  worthy  of  note, 
that  in  Nova  Zembla  and  Spitzbergen  "it  is  sometimes 
heard  to  thunder."  Contrast  the  general  meteorological  phe- 
nomena of  the  polar  regions  with  those  of  the  torrid  zone. 
They  present  the  extremes  of  a  habitable  earth,  and  these 
extremes,  we  believe,  are  caused  by  the  inequality  in  the 
degree  of  those  transfers  of  force,  which  give  both  the  peri- 
odic and  the  occasional  alternations  of  the  elements  ;  and,  in 
tracing  out  the  causes  of  meteorological  phenomena,  we  are 
led  to  look  to  these  transfers  of  force.  For  instance,  if  we 
would  know  what  causes  the  gush  of  rain  accompanying  the 
flash  of  lightning,  we  should  consider  that  the  cloud  is 
formed  from  water  by  the  reception  of  force,  that  by  its  rapid 
condensation  force  is  given  out  suddenly  in  the  flash  of  light- 
ning, and  that  the  condensed  water  falls  at  one  and  the  same 
time  ;  —  they  are  the  different  phases  of  the  same  act. 

We  regard  the  barometer,  not  as  indicating  the  pressure 
of  a  column  of  air  over  it,  but  as  indicating  the  level  of  its 
rotation,  and  we  believe  that  its  oscillations  at  the  same  ap- 
parent altitude  mark  the  rising  and  falling  surface  of  the 
earth.  By  this  view  we  have  an  explanation  of  the  connec- 


MECHANICAL  PHILOSOPHY.  271 

tion  of  the  changes  of  the  height  of  the  mercury  with  the 
changes  of  the  weather. 

The  rise  and  fall  of  the  mercury  denote  the  different 
levels  at  which  every  part  of  the  surface  of  the  earth  moves 
in  its  diurnal  round.  By  the  rise  of  any  portion  of  the 
earth's  crust  more  force  for  motion  is  required,  by  its  fall 
less  is  needed.  In  the  one  case  force  is  given  out  or  trans- 
ferred from  the  earth  ;  in  the  other  it  is  absorbed.  A  high 
range  of  the  barometer  indicates  a  low  surface  and  dry 
weather ;  a  low  range  shows  a  high  surface  and  wet  weather. 
A  high  surface  therefore  withdraws  force  from  the  vapor  of 
the  air,  and  it  condenses ;  from  the  low  surface  force 
escapes  from  the  water  in  the  form  of  vapor.  To  repeat 
the  idea,  a  high  surface  of  rotation,  indicated  by  the  low 
barometer,  withdraws  the  sustaining  force  of  vapor;  a  low. 
surface,  on  the  other  hand,  indicated  by  the  high  barometer, 
supplies  the  force  which  gives  tension  to  the  vapor.  The 
act  of  withdrawing  force  by  a  rise  of  the  earth  would  recon- 
dense  vapor ;  the  act  of  supplying  force  by  a  fall  of  the 
earth  would  sustain  the  vapor  in  high-floating  clouds.  Thus 
is  explained  the  varying  height  at  which  the  clouds  float,  now 
enveloping  the  surface  with  fog  and  mist,  and  now  rising 
miles  above  us,  with  sharp  and  well  defined  outlines. 

Water  exists  in  the  atmosphere  in  two  states  ;  in  the 
one,  at  its  greatest  tension  it  is  the  unobserved  humidity  of 
the  air ;  in  the  other,  it  is  partially  condensed  in  the  form 
of  mist,  or  fog,  or  more  properly  vapor.  The  humidity  of 
the  air  is  shown  by  the  condensation  that  takes  place  in  the 
driest  weather,  on  the  outside  of  a  vessel  containing  water 
so  much  cooler  than  the  atmosphere  as  to  cause  this  conden- 
sation. The  dew-point  is  that  degree  of  difference  of 
heat  between  the  atmosphere  and  the  earth,  which  is  suffi- 


272  OUTLINES   OF  A   SYSTEM   OF 

cient  to  cause  the  condensation  of  the  humidity  of  the  air 
into  dew.  The  formation  of  vapor  and  its  recondensation 
are  not,  however,  the  transfer  of  sensible  heat  only.  They 
are  caused  by  the  transfer  of  this  heat,  of  electricity,  of 
galvanism,  and  of  the  magnetic  fluid,  all  of  which  are  but 
phases  of  the  dynamic  power  of  the  world,  —  branches  of 
the  great  current  of  force  by  which  the  equilibrium  of 
motion  is  preserved.  Thus  dew  is  formed  by  night  on 
those  parts  of  the  earth  which,  being  turned  away  from  the 
sun,  require  the  greater  force  of  revolution  on  account  of 
their  enlarged  orbit.  It  is  not  formed  in  cloudy  weather, 
because  from  local  causes,  as  evinced  by  the  very  existence 
of  the  clouds,  the  force  which  would  be  given  out  from  the 
formation  of  the  dew  is  not  required.  Even  the  vapor 
which  rises  from  a  water-fall  gives  to  the  air  of  its  vicinity 
an  electrical  state  different  from  that  of  the  adjacent  atmo- 
sphere. The  electrometer  proves  that  the  electrical  state 
of  the  air  changes  with  the  condensation  that  causes  the  fall 
of  rain.  "  In  fogs,  and  in  the  commencement  of  a  fall 
of  snow,"  says  Humboldt,  "  I  have  seen  by  a  very  Ions? 
series  of  observations,  the  previously  permanent  positive 
electricity  rapidly  .pass  into  the  negative,  both  at  the  plains 
of  the  colder  zones  and  at  great  elevations  between  the 
tropics."  We  know  that  the  tension  of  vapor  has  its  two 
maxima  and  minima  daily,  which  correspond  to  the  maxima 
and  minima  of  the  diurnal  alternations  of  the  surface  of 
the  earth.* 


*  We  have  frequently  alluded  to  the  condensation  of  vapor  by  moun- 
tains and  high  lands,  for  the  reason  that  they  require  a  greater  force  of  rota- 
tion. The  fact  is  thus  clearly  expressed  hy  M.  Guyot :  "  The  mountain 
chains  are,  then,  the  great  condensers  placed  by  nature,  here  and  there 
along  the  continents  to  rob  the  winds  of  their  treasures,  to  act  as  reservoirs 


MECHANICAL   PHILOSOPHY.  273 

From  this  cause  we  have  the  different  character  of  the  two 
opposite  winds  of  our  climate,  the  north-west,  and  the  south- 
east. The  one  is  the  polar  current,  in  which  the  air  comes 
from  the  north,  inclining  to  the  east  because  of  accelerated 
rotation  ;  in  the  other  the  air  comes  from  the  south,  with  an 
inclination  to  the  west  from  retarded  rotation.  The  one  has 
more,  the  other  less,  than  the  normal  force ;  the  one  by  the 
additional  force  increases  the  tension  of  vapor,  the  other  by 
the  diminished  force  decreases  it ;  the  one  imparts  force, 
and  water  passes  into  vapor,  the  other  withdraws  force  and 
the  vapor  condenses  ;  the  one  usually  gives  dry  and  clear 
weather,  the  other,  fog,  rain  or  snow.  Of  course  the  char- 
acter of  the  wind  is  modified  in  some  degree  by  its  passage 
over  water  or  land,  but,  notwithstanding  this  modification, 
the  characteristic  difference  of  these  winds  remains,  and  is 
proved,  not  only  by  the  different  tension  of  vapor,  but  by 
their  contrary  effects  on  the  animal  organization.  The  one  is 
an  exhilarating,  exciting  wind  ;  the  other  is  unelastic  and 
depressing.* 

for  the  rain  waters,  and  to  distribute  them  afterwards,  as  they  are  needed 
over  the  surrounding  plains."  .  .  .  "  But  as  we  have  .said  the  plateaus  have 
also  a  marked  effect  on  the  distribution  of  the  rain  waters.  Their  borders 
act  as  mountains."  .... 

"  The  effect  of  the  condensation  in  the  supply  of  the  force  of  rotation  is 
shown  by  the  change  it  produces,  in  the  character  of  the  winds  of  the 
tropics.  The  trade  wind  is  from  retarded  rotation  of  the  atmosphere. 
The  copious  condensation  of  the  moisture  of  the  air  into  clouds,  and  of  the 
clouds  into  rain,  at  the  rainy  season,  breaks  up  the  trade  winds.  When 
the  trade  wind  blows  with  its  accustomed  regularity  there  is  no  condensa- 
tion, 'the  air  is  dry  and  the  atmosphere  cloudless.'  The  periodical  rains 
of  the  tropics  follow  the  sun,  or  rather  follow  the  extreme  diameter  of  the 
revolution  of  the  earth." 

*  "  This  conflict  of  polar  and  equatorial  winds,"  says  M.  Guyot,  "  oppo- 
site in  character  and  direction,  gives  to  our  climate  one  of  its  most  char- 


274  OUTLINES    OF   A   SYSTEM    OF 

How  various  are  the  considerations,  how  numerous  are 
the  facts,  which  seem  to  support  the  position,  that  vaporization 
and  condensation  are  among  the  means  of  preserving  the 
equilibrium  of  motion  !  The  bright  and  clear  sky,  the  dark 
and  lowering  cloud,  dry  weather,  fog  and  mist,  the  parched 
earth,  and  the  copious  rains,  —  these  ever- varying  alterna- 
tions speak  to  us  not  of  the  changing  heat  of  the  sun  only, 
nor  of  a  lighter  or  heavier  atmosphere,  but  of  the  ever-pass- 
ing currents  of  force,  and  through  them  of  the  varying  level 
of  rotation  as  indicated  by  the  barometer.  Who  can  recall 
the  high  electrical  state  of  a  clear  day  in  midwinter  or  mid- 
summer, the  damp  easterly  winds  of  spring,  or  the  murky 
atmosphere  of  the  dog-days,  and  not  perceive  that  the  ten- 
sion of  vapor  is  determined  in  some  degree  by  the  varying 
motions  of  the  earth,  as  she  speeds  in  the  different  parts  of 
her  orbit  ? 

We  divide  the  winds  into  two  classes,  —  the  normal  winds 
of  the  region  where  they  occur,  and  the  occasional  winds 
arising  from  local  disturbances  of  the  level  of  rotation. 
At  the  extremes  of  rotary  velocity,  in  the  equatorial  and 
polar  regions,  the  prevailing  winds  are  of  the  former  class. 
There  are  the  regular  tropical  winds,  and  the  regular  polar 
currents  of  the  northern  and  southern  regions,  arising  from 
the  retarded  or  accelerated  motion  of  the  atmosphere. 
Midway  there  is  no  prevailing  atmospheric  current,  and  the 
winds  arising  from  local  changes  appear  fitful  and  capricious. 
The  regular  winds  are  far-pervading,  and  blow  in  right  lines 

acteristic  features,  its  changeableness,  its  extreme  variety  of  temperature, 
of  dryness  arid  moisture,  of  fair  weather  and  foul."  .  .  .  .  "  The  polar 
winds  will  prevail  in  a  country  and  will  endanger  the  crops  by  the  pro- 
longed dryness  of  the  atmosphere,  while  further  east  or  west,  the  trade 
winds  will  spread  fertility  by  beneficent  rains." 


MECHANICAL  PHILOSOPHY.  275 

or  in  curves  of  wide  radii ;  the  occasional  cover  a  more  lim- 
ited range,  moving  in  narrow  circles.  The  one  class  has  the 
character  of  uniformity  ;  those  of  the  other  are  storm  winds. 
Thus  the  hurricane  of  the  tropics  is  usually  a  westerly  wind ; 
in  our  regions,  and  especially  further  north,  the  easterly 
winds  bring  the  most  frequent  tempests.  Storms  being  in- 
duced by  sudden  changes  of  level,  the  air  moves  with  the 
newly  acquired  force  in  a  circle,  and,  as  the  depression 
propagates  its  undulation,  the  circle  advances.  The  cause 
preceding  the  effect,  and  the  change  of  level  being  the 
cause,  the  barometer  indicates  the  approaching  tempest  by 
its  sudden  oscillation.  Storms  accompanying  the  prevailing 
winds  are  occasioned  by  local  disturbances  accelerating 
these  winds. 

We  regard,  then,  the  changes  in  the  direction  and  inten- 
sity of  the  winds,  as  determined  by  the  transfers  of  force 
from  altered  levels  of  rotation,  and  by  changes  in  the  position 
of  the  earth.  The  theory  which  we  present  for  consideration 
will  not  only  thus  explain  the  great  phenomena  of  the  weather, 
but  also  many  of  its  apparently  fitful  changes.  We  have  a 
reason,  for  instance,  for  the  want  of  permanency  of  fair 
weather,  when  the  wind  of  our  climate  lacks  in,  as  it  is  called, 
or  comes  round  by  the  north  to  the  westward  after  an  east- 
erly storm  ;  for  this  takes  place  by  a  local  change  of  level, 
not  by  the  restoration  of  the  normal  wind  as  determined  by 
the  season  and  by  geographical  position.  We  have  also  the 
reason  for  the  equinoctial  storms,  which  result  from  a  change 
of  the  position  of  the  earth  relatively  to  the  sun,  the  centre 
of  revolution,  giving  a  new  direction  to  the  flow  of  force  ; 
and  also  for  the  changes  of  the  weather  connected  with  the 
phases  of  the  moon.  The  moon  is  the  people's  barometer  ; 
and  we  believe  that  it  not  only  widens  our  local  system  and 


276  OUTLINES   OF  A   SYSTEM   OP 

increases  the  flow  of  force,  but  periodically  increases  and 
diminishes  the  intensity  of  the  flow.  Changes  of  weather 
result  from  the  transfers  of  force,  and  these  are  determined 
by  the  motion  of  the  world,  as  the  moon  and  the  earth  swerve 
sympathetically  in  their  common  orbit  of  revolution. 

We  pass  to  the  consideration  of  other  phenomena,  which 
seem  to  strengthen  the  position  that  the  different  degrees  of 
the  tension  of  vapor,  and  the  direction  and  intensity  of  the 
winds,  are  determined  by  the  degree  of  force  relatively  pos- 
sessed by  earth,  water,  and  air,  and  that  the  tempest  and 
storm  are  but  transfers  to  preserve  the  equilibrium  of 
motion,  —  that  they  are  not  accidents,  but  the  consequence 
of  those  alternations  which  give  to  the  elements  their  life 
and  activity,  —  change  within  a  fixed  limit,  creating  the 
"  agreeable  fitness  "  of  all  things  in  this  beautiful  home  of 
man. 

There  have  been  earthquakes  in  every  part  of  the  world, 
and  they  are  not  rigorously  confined  to  any  season  of  the 
year.  They  are,  however,  by  far  the  most  frequent  in  the 
torrid  zone,  and  at  the  commencement  of  the  rainy  season, 
at  the  vernal  and  autumnal  equinoxes,  and  at  the  changes  of 
the  monsoons.  "We  trace  them,  then,  chiefly  in  regions 
where  the  transfers  of  force  are  the  greatest,  and  at  the 
times  of  such  changes  in  the  earth's  position  as  vary  her 
motion,  and  give  alternations  to  the  flow  of  force.  An  earth- 
quake sometimes  changes  the  level  of  rotation  of  a  distant 
part  of  the  earth,  in  addition  to  the  local  convulsions  which 
it  produces.  After  a  violent  earthquake  in  the  island  of 
Sumatra,  Darwin  traced  out,  as  a  consequence  of  it,  a  sub- 
sidence of  land  at  a  point  six  hundred  miles  distant.  There 
have  been  permanent  elevations  of  a  vast  extent  of  coast  by 
this  means.  Earthquakes  are  not  always  preceded  by 


MECHANICAL    PHILOSOPHY.  277 

atmospheric  changes,  but  are  invariably  succeeded  by  rains, 
even  when  rain  is  out  of  season  where  they  occur.  Very 
little  is  known  of  the  cause  of  earthquakes  ;  but  we  will  quote 
a  remark  of  Pliny,  which  is  somewhat  in  accordance  with 
our  views.  "  They  are  because  the  elastic  forces,  concussive 
by  their  tension,  accumulate  in  the  earth  when  they  are 
absent  in  the  atmosphere ; "  in  other  words,  the  force  of 
motion  is  too  great  for  the  orbit  of  rotation,  and  the  earth 
rises  suddenly  and  convulsively. 

Volcanoes  are  attended  with  the  same  phenomena  as 
earthquakes.  In  their  periods  of  activity,  beside  the  throw- 
ing up  of  great  volumes  of  lava  and  other  substances,  and 
the  local  agitations  produced,  there  is  frequently  an  agitation 
of  the  earth,  which  is  perceived  often  at  a  very  great  dis- 
tance. The  eruption  of  a  volcano  is  attended  "  with  fierce 
winds  and  deluging  rains."  Stromboli  was  considered  as 
the  dwelling-place  of  -ZEolus,  the  regulator  of  the  winds ; 
and  the  fishermen  on  the  coast  were  able  to  foretell  the 
weather  by  its  eruptions,  or  by  the  premonitory  symptoms 
of  an  eruption.  The  connection  between  the  eruption  of 
even  a  small  volcano  and  the  state  of  the  barometer  is 
now  generally  acknowledged.  The  earth  in  the  vicinity 
changes  its  level  before-  and  during  the  eruption. 

The  connection  between  the  undulations  of  the  surface  of 
the  earth  and  the  weather,  thus  indicated  by  the  earthquake 
and  the  volcano  is  not  an  exception  to  a  general  law.  It 
is,  if  we  may  be  allowed  the  expression,  the  abnormal 
action  of  the  law  ;  it  is  a  fact,  standing  as  it  were  unnat- 
urally, out  of  position,  thereby  distinctly  showing  the  action 
of  a  law  otherwise  hidden  under  the  uniformity  of  its  usual 
routine.  This  known  sympathy  between  the  weather  and 
the  change  of  level  of  a  part  of  the  earth's  surface  is  not 

24 


278  OUTLINES   OF  A   SYSTEM   OF 

, 

occasional  or  accidental.  By  these  convulsions  sudden 
changes  in  the  weather  are  produced ;  but  it  is  also  varied 
by  more  gentle  alternations.  It  is  by  the  transfers  of  force 
that  the  rain  falls  and  the  winds  blow.  It  is  by  the  health- 
giving  readjustments  of  the  force  of  motion  that  we  have 
the  occasional  storm ;  it  is  by  the  equable  flow  of  the  life  of 
the  world  that  we  have  the  usual  serenity  of  the  face  of 
Nature. 

The  mean  temperature  of  a  season  often  changes  over  a 
large  portion  of  the  earth.  We  have  perhaps  a  cold  sum- 
mer, or  a  comparatively  mild  winter.  This  inequality 
spreads  as  from  a  centre.  As  we  go  from  this  centre,  the 
excess  or  deficiency  of  heat  decreases  ;  and,  when  we  pass 
the  limit,  the  increase  or  diminution  changes  conversely,  and 
we  have  the  opposite  increasing  alteration  of  the  mean  tem- 
perature. This  undulation  of  the  curve  of  mean  tempera- 
ture moves  mainly  from  north  to  south.  How  is  this  undu- 
lation to  be  accounted  for  ?  The  sun  shines  as  in  former 
seasons,  nor  can  atmospheric  pressure  be  tortured  into  a 
reason. 

We  present  another  phenomenon  connected  with  the  trans- 
mission of  force,  for  a  hasty  examination.  The  aurora  bo- 
realis  of  our  northern  regions  appears  to  be  an  arch  or 
circuit  of  the  "  magnetic  force,"  spanning  a  portion  of  the 
earth,  as  if  conducting  the  flow  from  whence  it  abounds  to 
where  it  is  needed  without  passing  through  the  intermediate 
parts.  The  shooting  cylinders  of  rays  have  been  compared 
to  the  flame  which  arises  in  the  closed  circuit  of  the  voltaic 
pile  between  two  points  of  carbon.  Is  it  not  a  flame  stretch- 
ing between  the  surcharged  and  undercharged  parts  of  the 
earth  or  atmosphere  ?  That  it  is  a  passage  of  what  is  called 
the  galvanic  fluid,  we  know ;  for  it  disturbs  the  magnetic 


MECHANICAL    PHILOSOPHY.  279 

needle,  which  often  points  to  the,  corona  of  the  arch.  It 
indicates  a  disturbed  electric  condition  ;  and,  while  the  light- 
ning in  the  electrical  storm  shows  a  sudden  transfer  of 
force,  the  aurora  represents  a  more  gradual  adjustment  of  the 
equilibrium.  It  does  not  occur  in  the  night-time  only,  but 
its  path  may  often  be  traced  by  day  in  a  circle  of  half- 
illuminated  clouds.  It  is  usually  accompanied  by  a  high 
barometer  and  great  tension  of  vapor,  —  by  all  the  phases  of 
motion  which  indicate  more  than  the  usually  present  force. 
For  this  reason  we  consider  it  as  a  distribution  of  the  mag- 
netism of  the  polar  regions,  passing  over  an  already  well 
supplied  region.  With  us  the  aurora  most  frequently  ap- 
pears after  an  easterly  wind  has  subsided,  and  a  clear  wind 
from  the  northwest  has  begun  to  diffuse  the  spare  force  of 
the  more  northerly  regions. 

The  transfer  of  force  shows  itself  often  in  a  light  which 
follows  its  path,  and  attends  its  movements.  There  have 
been  luminous  fogs ;  there  are  often  clouds  half-illumin- 
ated, shining  not  by  reflected  light,  but  by  their  own  emana- 
tions. Without  any  other  assignable  cause,  whole  nights,  as 
in  Italy  and  the  north  of  Germany  in  the  year  1831,  have 
been  so  light  that  the  smallest  print  could  be  read  at  mid- 
night. What  shall  we  say  of  the  phosphorescence  of  the  sea, 
the  waters  of  which,  disturbed  by  the  prow  of  a  ship,  with 
a  fresh  wind  and  clear  sky,  are  like  waves  of  light  ?  The 
presence  of  animalcules  will  not  account  for  this  ;  for  a  certain 
electrical  state  of  the  atmosphere  always  attends  it. 

But  we  must  leave  this,  to  us,  interesting  branch  of  our 
inquiry.  We  know  that  we  must  have  often  erred  in  the 
application  of  the  principles  which  we  present ;  but  errors  of 
application  should  not  detract  from  the  value  of  a  general 
principle.  Our  hope  is,  that  in  our  illustrations  we  may 


280  OUTLINES   OF   A   SYSTEM   OF 

have  been  so  far  successful  as  to  give  the  necessary  explan- 
ations of  our  views,  so  that  they  may  be  examined  and 
tested,  and,  if  found  worthy,  be  applied  by  those  who,  from 
years  of  devotion  to  scientific  pursuits,  are  more  competent  to 
work.  Atmospheric  changes  seem  capricious,  as  if  without 
the  law  ;  but  this  must  be  in  appearance  only.  The  facts 
which  nature  presents  are  never  out  of  rule.  As  science  ad- 
vances, the  discordant  and  conflicting  phenomena  decrease  in 
number  ;  the  periodical,  unvarying,  regulated,  become  more 
numerous  ;  order  extends  itself,  and  accident  gradually 
puts  on  the  appearance  of  design.  It  appears  as  if  order 
was  created  by  the  sympathy  of  the  mind  with  nature  ;  but 
now  and  ever,  whether  we  perceive  it  or  not,  a  sovereign 
law  is  completely  and  perfectly  obeyed.  The  change  is  in 
ourselves  ;  and  the  perfection  of  philosophy  is  this  transfer 
of  the  order  without  to  order  within,  the  regularity  and 
harmony  of  nature  giving  distinctness  and  definiteness  to 
thought. 

Before  we  close  this  chapter,  we  will  give  the  reasons  why 
we  disbelieve  altogether  in  the  existence  of  the  supposed 
intense  heat  of  the  interior  of  our  globe.  This  heat  would 
be  a  useless  force,  and,  so  far  as  the  action  of  nature  can  be 
traced  out,  there  is  found  no  unemployed  or  reserved  dyna- 
mic power.  All  force  is  in  unremitting  action.  There  is 
no  waste  energy,  none  pent  up,  confined,  laid  by  for 'ulte- 
rior use.  The  sensible  or  diffusible  heat  of  the  planet 
appears  to  come  from  the  vital  force  constantly  circulating 
through  every  part  of  it,  and  through  every  element  which 
rests  upon  it,  or  envelops  it.  A  flow  of  heat  from  the  sun, 
the  centre  of  its  revolution,  warms  its  surface,  and  beneath 
its  crust  the  magnetism  of  the  earth,  from  the  decrease 
of  rotary  force,  gradually  becomes  sensible  heat  as  we 


MECHANICAL   PHILOSOPHY.  281 

descend.  The  magnetic  elements  of  any  portion  of  the 
globe  may  be  calculated  from  the  heat  of  that  portion,  and 
conversely  the  distribution  of  the  magnetic  force  may  be 
calculated  from  the  distribution  of  heat.  Force  exists  every- 
where as  it  is  required,  and  resolves  itself  into  sensible  heat 
no  further  than  by  the  transfers  needed  for  readjust- 
ments of  equilibrium.  The  normal  action  of  the  needle  is 
from  the  steady  flow  of  force,  and  its  variations  of  intensity 
are  from  the  periodic  or  occasional  variations  in  the  current. 
On  the  other  hand,  the  supposition  of  intense  internal  fire 
requires  the  belief  of  a  permanent  inequality,  —  an  abiding 
want  of  equipoise.* 

We  shall  be  pointed  to  the  earthquake  and  asked,  whence 
its  power  ?  We  reply,  it  is  a  sudden  restoration  of  equili- 
brium, proving  that  the  globe  does  not  bear  even  slight 
irregularities,  but  frees  itself  of  all  superfluous  power.  In 
relation  to  the  volcano,  we  have  the  same  answer ;  and 
further,  the  force  or  heat  exhibited  by  the  earthquake  and 
volcano  is  altogether  insufficient,  taking  into  consideration 
the  magnitude  of  the  globe,  to  indicate  that  its  interior  is  a 
mass  of  liquid  fire. 

We  shall  be  pointed  to  the  crystalline  structure  of  the 
Plutonic  rocks,  as  proof  that  these  rocks  were  once  fluid 
from  intense  heat,  and  to  the  upturned  strata  of  the  globe, 
to  its  distorted  mountain  ridges,  as  evidence  that  heat  was 

*  The  writer  of  a  valuable  scientific  article  in  the  fifth  volume  of  the 
North  British  Review,  expresses  a  somewhat  similar  idea.  He  remarks,  — 
"  When  we  look  at  the  system  of  isothermal  curves  surrounding  the  poles 
of  revolution,  and  mark  their  coincidence  with  the  magnetic  poles  of  the 
earth,  and  their  similarity  to  the  isodynamical  magnetic  curves,  we  are 
disposed  to  view  so  remarkable  a  phenomenon,  as  the  result  of  a  physical 
condition  of  the  earth  itself,  and  produced  by  causes  connected  with  its 
magnetic,  or  galvanic,  or  chemical  agencies." 
24* 


282  OUTLINES 'OF  A  SYSTEM  OF 

necessarily  the  producing  cause  of  the  convulsion  which  up- 
lifted them.  Although  we  know  that  crystallization  takes 
place  at  times  without  sensible  heat,  by  the  magnetic  power, 
we  are  ready  to  admit  that  in  the  hands  of  God  heat  may 
have  been  the  instrument  of  re-creation ;  but,  because  force 
under  this  form  may  have  been  His  means  of  action,  it  does 
not  follow  that  it  now  remains  pent  up  in  the  bowels  of  the 
earth.  The  same  force  under  other  forms  of  power  may  be 
doing  His  will  in  the  preservation  of  the  globe  which  he  fitted 
for  the  home  of  man. 

But  how  little  of  the  interior  of  the  earth  is  known  !  Man 
has  penetrated  a  few  feet  only.  The  upraised  mountain 
which  is  supposed  to  indicate  its  deeper  structure,  may  have 
been  changed  by  its  elevation,  and  may  not  represent  the 
greater  depth.  We  know  nothing  of  the  beds  of  the  ocean, 
nothing  of  the  internal  condition  of  the  earth.  Scientific 
men  in  Europe  are  now  disputing  whether  this  globe  is  a 
hollow  sphere,  or  a  solid  mass,  or  whether  its  interior  is  com- 
posed of  molten  fire.  We  venture  to  predict  that  the  ulti- 
mate decision  will  not  be  in  favor  of  the  latter  supposition. 
From  analogy  we  believe  in  its  perfect  regularity  of  struc- 
ture ;  the  distortions  and  bendings  of  its  upper  rocks  may 
be  surface-changes  only. 

There  can  be  nothing  accidental  in  the  position  of  any 
portion  of  the  earth  ;  and,  when  we  recur  to  the  fact,  that 
for  hundreds  of  miles  the  extended  quarries  of  rock  preserve 
one  direction  of  dip,  and  one  angle  of  stratification,  —  when 
we  remember  the  order  of  the  superposition  of  the  various 
strata  all  over  the  world,  we  cannot  regard  the  form  of  the 
earth  as  given  to  it  by  the  accidental  heaping  together  of 
heterogeneous  masses  of  mineral,  convulsively  commingled 
from  the  bursting  of  its  crust  by  the  action  of  internal  fire. 


MECHANICAL  PHILOSOPHY.  283 

Science  with  its  present  knowledge  has  ascertained  a  more 
perfect  order  than  chance  explosions  could  produce. 

In  a  previous  chapter  we  alluded  to  the  recently  discov- 
ered magnetic  properties  of  crystals.  The  experimentalist 
found  that  different  crystals  possess  this  virtue  in  varying 
degrees,  and  that,  when  suspended  by  delicate  threads  of  silk, 
some  point  to  the  magnetic  poles,  and  some  to  the  poles  of 
the  earth's  axis,  while  some  act  as  declination-needles.  The 
direction  which  the  crystal  takes  is  determined  by  the  di- 
rection of  its  natural  cleavages.  Is  not  this  earth,  as  it 
were,  suspended  and  free  to  move  under  the  impulse  of 
magnetic  force  ?  Is  not  the  very  lay  and  dip  of  its  mineral 
body,  —  the  stratification  of  its  framework  of  rock,  so 
arranged  that  the  flow  of  force  may  guide  and  determine  its 
motion,  as  the  minor  stream  of  magnetic  power  influences 
the  direction  of  the  crystal  ?  Its  structure  may  have  been 
given  to  it  to  adapt  it  for  its  required  movements,  and  what 
appears  to  us  as  the  accidental  position  of  its  parts,  may  be 
as  much  induced  by  law  as  the  symmetry  of  the  brightest 
gem. 


CHAPTER  XI. 


"IN  ALL  OTHER  SCIENCES  THE  PROPOSITIONS  THAT  WE  ATTEMPT  TO 
ESTABLISH  EXPRESS  FACTS  REAL  OR  SUPPOSED  ;  IN  MATHEMATICS 
THE  PROPOSITIONS  THAT  WE  ATTEMPT  TO  DEMONSTRATE  ONLY 
ASSERT  A  CONNECTION  BETWEEN  CERTAIN  SUPPOSITIONS  AND 
CERTAIN  CONSEQUENCES." Stewart. 

IT  is  supposed  by  many  that  the  theory  of  universal  grav- 
itation has  been  mathematically  demonstrated,  and  therefore 
stands  incontrovertible.  These  questions  will  be  asked  :  is 
not  the  mutual  attraction  of  the  heavenly  bodies  the  very 
basis  of  mathematical  astronomy,  by  which  the  position  of 
every  sphere  is  determined ;  and  does  not  observation  confirm 
the  reasoning,  and  of  course  the  theory  on  which  the  rea- 
soning is  founded  ? 

The  hand  of  a  clock  may  point  to  the  time  of  noon,  and 
thus  indicate  the  position  of  the  sun>  while  neither  the 
movement  of  the  wheels,  nor  the  movement  of  the  pendu- 
lum which  governs  them,  conforms  in  the  least  to  the  motions 
of  the  sun.  Thus  mathematical  reasoning  may  track  out  the 
equable  motions  of  the  heavenly  bodies,  while  neither  the 
theory  on  which  the  process  is  founded,  nor  the  process 
itself,  in  the  least  degree  indicates  the  cause  of  the  motion. 
A  mathematical  process  is  at  times  even  aided  by  fiction, 
and  is  often  successful  when  the  theory  on  which  it  is  based 
is  known  to  be  the  very  opposite  of  truth. 

Under  the  Ptolemaic  theory  the  apparent  motion  of  the 


MECHANICAL  PHILOSOPHY.  285 

heavenly  bodies  was  considered  the  true  and  real  movement. 
The  earth  was  then  believed  to  be  the  motionless  centre 
around  which  the  universe  rolled.  With  this  assumption 
the  mathematician  could,  with  surprising  exactness,  project 
eclipses,  and  predetermine  the  relative  position  of  a  sphere 
at  any  given  future  time.  With  this  obviously  false  theory 
as  the  groundwork  of  calculation,  results  of  great  accuracy 
were  obtained.  This  idea  has  been  thus  clearly  expressed : 
"  Now  the  truth  is  that  this  complicated  and  fantastic  theory 
of  the  heavens,  [the  Ptolemaic,]  with  its  operose  contriv- 
ances of  eccentric  wheels,  and  circles  riding  on  circles,  and 
which  in  point  of  fact  is  false  from  beginning  to  end,  is  just 
as  correct  a  basis  for  astronomical  calculations,  as  the  sim- 
pler, more  beautiful,  and  more  truthful  system  of  Coperni- 
cus. The  language  of  Mr.  Whewell,  whose  authority  on 
a  point  like  this,  no  one  will  dispute,  is,  '  As  a  system  of  cal- 
culation it  is  not  only  good,  but  in  many  cases,  no  better 
has  been  discovered.7  7: 

The  character  of  the  mathematical  calculations,  which 
are  relied  upon  to  prove  that  the  theory  of  gravitation  is 
applicable  to  the  bodies  composing  the  solar  system,  may  be 
learned  by  the  following  quotation  from  the  History  of  the 
Inductive  Sciences  :  "  The  difficulty  of  doing  what  Newton 
did  may  be  judged  of  from  what  has  already  been  stated, 
that  no  one  with  his  methods  has  yet  been  able  to  add  any 
thing  to  his  labors  ;  few  have  undertaken  to  illustrate  what 
he  has  written,  and  no  great  number  have  understood  it 
throughout.  The  extreme  complication  of  the  forces,  and 
of  the  conditions  under  which  they  act,  makes  the  subject 
by  far  the  most  thorny  walk  of  mathematics.  It  is  neces- 
sary to  resolve  the  action  into  many  elements,  such  as  can 
be  separated ;  to  invent  artifices  for  dealing  with  each  of 


286  OUTLINES   OF   A   SYSTEM   OF 

these,  and  then,  to  recompound  the  laws  thus  obtained,  into 
one  common  conception.  The  moon's  motion,  for  instance, 
cannot  be  conceived  without  comprehending  a  scheme  more 
complex  than  the  Ptolemaic  epicycles  and  eccentricities  in 
their  worst  form  ;  and  the  component  parts  of  the  system, 
are  not  mere  geometrical  ideas  requiring  only  a  distinct 
apprehension  of  relations  of  space  to  hold  them  securely ; 
they  are  the  foundation  of  mechanical  notions,  and  require 
to  be  grasped  so  that  we  can  apply  to  them  sound  mechan- 
ical reasonings.  Newton's  successors,  in  the  next  genera- 
tion abandoned  the  hope  of  imitating  him  in  this  intense 
mental  effort ;  they  gave  the  subject  over  to  the  operation 
of  algebraic  reasoning,  in  which  symbols  think  for  us  with- 
out our  dwelling  constantly  on  their  meaning,  and  obtain 
for  us  the  consequences  which  result  from  the  relations  of 
space  and  the  laws  of  force,  however  complicated  be  the 
conditions  under  which  they  are  combined." 

Again ;  "  if  the  mathematical  calculations  of  the  unmixed 
effect  of  the  central  force  required  transcendent  talents, 
how  much  must  the  difficulty  be  increased  when  other  influ- 
ences prevented  those  first  results  from  being  accurately 
verified,  while  the  deviations  from  accuracy  were  far  more 
complex  than  the  original  action  !  If  it  had  not  been  that 
these  deviations,  though  surprisingly  numerous  and  compli- 
cated, were  very  small  in  their  quantity,  it  would  have  been 
impossible  for  the  intellect  of  man  to  deal  with  the  subject ; 
as  it  was,  the  struggle  with  its  difficulties  is  even  now  a  mat- 
ter of  wonder." 

"  And  even  the  possibility  of  doing  what  has  been  done, 
depends  on  what  we  call  accidental  circumstances,  —  the 
smallness  of  inclination  and  eccentricities  of  the  system, 
and  the  like.  If  nature  had  not  favored  us  in  this  way, 


MECHANICAL  PHILOSOPHY.  287 

La  Grange  used  to  say,  there  would  have  been  an  end  of 
geometry  in  this  problem. " 

With  a  full  admission  of  the  accuracy  of  the  results  of 
mathematical  reasoning  as  applied  to  astronomy,  it  does  not 
follow  that  the  spheres  attract  each  other.  An  aberration 
or  perturbation  of  the  earth,  calculated  from  the  increased 
nearness  of  the  sun,  may  be  correctly  calculated,  and  yet 
the  aberration  may  not  be  occasioned  by  any  attractive 
power  in  the  sun.  The  motion  of  the  earth  may  be  changed, 
because  of  the  greater  force  of  motion  relatively  to  the 
diameter  of  her  orbit.  The  navigator  finds  the  position  of 
his  ship  by  the  aid  of  the  imaginary  lines  of  latitude  and 
longitude  intersecting  each  other  ;  but  it  is  not  these  lines 
which  give  position  to  the  ship.  Thus  may  the  astronomer 
find  the  place  and  determine  the  motion  of  a  planet  by  ima- 
ginary forces,  —  the  one  acting  inward, the  other  outward; 
but  these  forces  do  not  give  position  to  the  star.  His 
calculation  might  be  more  difficult,  yet  no  less  certain,  if  in 
the  place  of  two  conflicting  forces  he  used  as  the  basis  of  his 
reasoning  but  one  force  giving  directly  the  form  of  the  orbit. 

The  arithmetical  calculator  takes  for  truth  the  simple 
relations  of  numbers.  He  believes  in  his  data  intuitively ; 
and  he  extends  these,  the  more  simple  relations,  to  the  more 
complex  ratios  and  values.  The  astronomical  mathemati- 
cian assumes  that  bodies  fall  by  the  attraction  of  the  earth, 
and  he  extends  tne  attraction  of  matter  to  the  spheres. 
This  extension  partakes  not  only  of  the  uncertainty  of  the 
premises,  but  also  of  the  uncertainty  which  may  arise  from 
errors  of  mathematical  reasoning.  The  assumption  may  be 
gratuitous,  and  the  process,  thus  intricate  and  complicated, 
may  be  defective.  Uncertainty  from  two  sources,  there- 
fore, attaches  to  his  conclusions.  The  results  of  this  math- 


288  OUTLINES   OF   A   SYSTEM    OF 

ematical  reasoning  come  not  with  the  authority  of  the 
multiplication  table.  There  is  a  vast  difference  between 
pure  mathematics  and  the  abstrusities  of  reasoning  which 
extend  mere  speculation,  by  symbols  that  think  for  the 
calculator.  The  assertion  that  two  and  two  are  four,  makes 
a  different  impression  on  the  mind  from  that  made  by  the 
calculations,  by  which  the  dynamical  laws  of  nature  are 
mathematically  handled.  Number,  quantity,  ratio,  consti- 
tute the  domain  of  mathematics.  In  these  it  is  absolute, 
while  it  is  the  aid,  the  coadjutor  only,  in  natural  philosophy. 

We  quote  the  following  from  Stewart's  Philosophy:  "  In 
pure  mathematics  when  the  truths  we  investigate  are  all 
coexistent  in  point  of  time,  it  is  universally  allowed  that  one 
proposition  is  said  to  be  in  consequence  of  another,  only 
with  a  reference  to  our  established  arrangements.  Thus 
all  the  properties  of  the  circle  might  be  as  rigorously  de- 
duced from  one  general  property  of  the  curve,  as  from  con- 
siderations derived  from  the  radii.  But  it  does  not  follow 
that  all  these  arrangements  would  be  equally  convenient ; 
on  the  contrary  it  is  evidently  useful  and  indeed  necessary 
to  lead  the  mind  as  far  as  is  practicable  from  what  is  sim- 
ple to  what  is  more  complex.  The  misfortune  is  that  it 
seems  impossible  to  carry  this  rule  universally  into  execu- 
tion, and  accordingly  in  the  most  elegant  geometrical  trea- 
tises which  have  yet  appeared,  instances  occur  in  which 
consequences  are  deduced  from  principles  more  complicated 
than  themselves." 

Every  one  in  the  least  acquainted  with  mathematical 
astronomy  is  aware  that  its  great  burthen  has  been  the 
process  of  correction.  Thus  the  mass  of  Jupiter,  his 
attractive  value,  has  been  calculated  and  recalculated  ;  and 
is  it  wonderful  that  in  all  the  changing  results  a  value 


MECHANICAL    PHILOSOPHY.  289 

should  at  last  be  hit  upon  that  would  bring  his  influence 
under  the  theory  of  gravitation  ?  The  operation  by  which 
such  results  are  obtained,  involves  the  process  of  integration, 
"  which  cannot  be  performed  in  an  immediate  manner,  since 
the  quantities  to  be  operated  upon  depend  upon  the  facts, 
and  thus  require  us  to  know  the  very  thing  which  we  have 
to  determine  by  the  operation.  The  result  must  be  got  at 
therefore  by  successive  proximations.  We  must  find  a 
quantity  near  the  truth,  and  then  by  the  help  of  this, 
another,  and  so  on."  Whewell  says,  "  The  form  in  which 
the  question  of  the  truth  of  the  doctrine  of  universal  gravi- 
tation now  offers  itself  to  the  mind  of  astronomers  is  this  : 
that  it  is  taken  for  granted  that  it  will  account  for  the  mo- 
tion of  the  heavenly  bodies,  and  the  question  is  with  what 
supposed  masses  it  will  give  the  best  account."  This  is  the 
same  as  if  it  were  asserted  that  twenty  plats  of  ground  con- 
tained an  equal  number  of  acres,  and,  this  being  taken  for 
granted,  the  surveyor's  question  is,  what  assumed  angles  of 
each  plat  will  best  conform  the  theory  to  his  calculations  of 
the  areas  ? 

But  if  the  mathematical  process  of  thought  could  embrace 
the  laws  of  force  and  motion, — could  extend  the  law  of 
falling  bodies  to  the  mutual  relations  of  the  planets,  there  is 
yet  no  determinate  law  under  the  theory  of  gravitation  to 
be  carried  up  from  the  earth.  The  law  of  the  uniformly 
accelerated  motion  of  a  falling  stone  has  no  application  what- 
ever to  the  equable  motion  of  the  heavenly  bodies,  and  the 
law  of  uniformly  accelerated  motion  is  the  only  principle 
which  the  fall  of  bodies  to  the  earth  has  yet  established. 

The  law  that  attraction  is  in  direct  proportion  to  the  mass 
of  matter  which  attracts,  and  in  inverse  proportion  to  the 
25 


290  OUTLINES   OF   A   SYSTEM   OF 

square  of  its  distance  from  that  which  it  attracts,  can  never 
be  proved  from  the  action  of  a  falling  body.  Bodies  falling 
to  the  earth,  without  reference  to  the  medium  in  which  they 
move,  fall  in  the  same  time  ;  a  heavy  pendulum  vibrates  in 
the  same  time  as  a  light  pendulum  with  the  same  arc  ;  the 
world  is  so  large  in  relation  to  falling  masses,  that  the  reci- 
procal attraction  cannot  be  observed,  and  all  that  is  known 
of  the  earth's  attraction  is,  that  all  falling  masses,  whatever 
be  their  quantity  of  matter  or  their  distance,  are  drawn  with 
equal  force.  By  the  theory,  indeed,  there  is  an  ounce 
weight's  difference  between  the  strength  of  the  earth's  at- 
traction for  one  ton  at  her  surface,  and  her  attractive  force 
for  this  ton  a  mile  above  her  surface  ;  but  this  is  too  small  a 
diminution  of  attraction  to  be  the  subject  of  accurate  expe- 
riment. To  test,  therefore,  the  theory  of  attraction  relatively 
to  mass  and  distance,  we  must  go  up  from  the  earth  to  the 
spheres.  There  again  is  another  defeat ;  for,  though  the 
relative  distances  of  the  heavenly  bodies  can  be  calculated, 
there  is  not  one  of  them  of  which  the  mass,  density,  or  at- 
tractive power  can  ever  be  known  ;  and  without  this  know- 
ledge there  is  no  proof  that  they  do  attract  according  to  mass 
and  distance.  They  attract  as  much  as  —  they  do  attract ! 
"  It  is  by  the  means  of  the  perturbations  of  the  planets," 
says  an  eminent  astronomer,  "  as  ascertained  by  observation, 
and  compared  with  theory,  that  we  arrive  at  a  knowledge  of 
the  masses  of  those  planets,  which,  having  no  satellites,  offer 
no  other  hold  on  them  for  that  purpose."  .  .  "  The  perturb- 
ations of  the  satellites  of  Jupiter  have  led,  and  those  of 
Saturn  will  doubtless  hereafter,  lead  to  the  proportion  of 
their  masses  to  their  primaries."  In  this  view,  all  difficult- 
ies are  avoided ;  the  spheres  do  attract  according  to  the 
law  of  mass  and  distance,  for  the  mass  is  of  a  changeable 


MECHANICAL    PHILOSOPHY.  291 

value  to  suit  the  theory  of  attraction.  Thus,  the  earth's 
diameter  is,  say  eight  thousand  miles,  the  moon,  say  two 
thousand  miles ;  the  mass  of  the  earth  being  one,  the  moon 
to  fit  her  for  her  attracting  office,  is  placed  at  0.125172. 
Bulk  and  distance  are  of  no  consequence  whatever ;  for  the 
mass  of  any  sphere  is  so  fixed  as  to  make  all  things  conform  to 
a  law,  which  is  not  indicated  by  experiment  or  accurate  obser- 
vation. But  even  now  there  are  difficulties,  and  ever  have 
been.  Says  Herschell,  "  the  curious  and  complicated  effect 
of  perturbation  has  given  more  trouble  to  geometers  than 
any  other  part  of  the  lunar  theory.  Newton  himself  had 
succeeded  in  tracing  that  part  of  the  motion  of  the  apogee 
which  is  due  to  the  direct  application  of  the  radial  force, 
but  finding  it  only  half  what  observation  assigns,  he  appears 
to  have  abandoned  the  subject  in  despair.  Nor  when 
resumed  by  his  successors,  did  the  inquiry  for  a  very  long 
period  assume  a  more  promising  aspect,  and  strong  doubts 
were  excited  whether  this  feature  of  the  lunar  motion  could 
be  explained  at  all  on  the  laio  of  gravitation"  It  was 
afterwards  settled  by  taking  more  properly  into  account  the 
tangential  force. 

There  was,  too,  a  difficulty  with  the  secular  acceleration  of 
the  moon's  mean  motion,  "  which,  like  the  great  equation  of 
Jupiter  and  Saturn,  had  been  long  the  subject  of  toilsome 
investigation.  Some  were  again  on  the  point  of  declaring 
the  theory  of  gravitation  inadequate  to  its  explanation,  and 
others  were  for  rejecting  altogether  the  evidence  on  which 
it  rested."  In  this  dilemma,  La  Place  stepped  in  to  rescue 
astronomy  from  its  reproach.  There  was  a  difficulty,  too,  in 
some  of  the  relative  motions  of  Jupiter  and  Saturn,  "  at 
one  time  too  hastily  regarded  as  almost  subversive  of  the 
doctrine  of  gravitation" 


292  OUTLINES    OF   A    SYSTEM    OF 

Not  many  years  ago  doubts  were  entertained  by  the 
German  astronomers,  whether  the  law  of  gravitation  were 
rigorously  true  with  regard  to  the  planetary  bodies.  Some 
calculations  showed  that  the  attraction  of  Jupiter  as  mani- 
fested by  the  perturbations  of  the  small  planets,  Juno,  Vesta, 
and  Pallas,  was  different  from  the  attraction  on  his  own 
satellites.  They  inclined  to  the  opinion  that  the  attraction 
of  the  spheres  might  be  elective.  But  this  was  met  by  a 
new  determination  of  the  mass  of  Jupiter  by  Mr.  Airy. 

One  thing  is  certain,  that  it  was  a  work  of  great  time 
and  labor,  so  to  arrange  the  masses  of  the  spheres,  and  so 
to  construct  the  mathematical  theory,  that  the  perturbations 
could  be  made  to  conform  to  the  hypothesis  of  gravitation ; 
and  that  now  the  mathematical  theory  is  far  in  advance  of 
observation,  bearing  in  a  degree  the  same  relation  to  per- 
turbation, that  the  mathematical  theory  of  the  tides  bears  to 
the  observed  facts  of  the  tides.  There  is  perhaps  much  to 
cause  the  astronomer  who  believes  in  gravitation,  to  believe 
also  that  perturbation  is  caused  by  mutual  attraction  ;  and 
yet  these  perturbations  could  not  of  themselves,  apart  from 
theory,  have  led  to  the  theory,  nor  can  they  prove  the 
theory  of  themselves,  for  the  reason  that  the  masses  of  the 
spheres  are  determined  by  the  theory  itself. 

We  form  the  most  definite  idea  of  perturbation  by  the 
analogy  before  alluded  to,  presented  by  a  distinguished 
astronomer :  —  "  The  laws  of  perturbation  will  be  indicated 
by  supposing  all  the  spheres  to  be  connected  by  imperfectly 
elastic  material  ties.  By  their  motion  there  would  be  a 
forced  vibration  or  oscillation  communicated  through  the 
whole  system  of  worlds."  Perturbation  is  periodic  and 
diffusible  ;  the  amount  of  eccentricity  is  equally  divided,  — 
what  has  been  called  the  "  eccentricity  fund  "  is  the  pro- 


MECHANICAL   PHILOSOPH?.  293 

perty  of  all  in  a  certain  fixed  ratio.  There  is  nothing  erratic, 
incidental,  accidental  about  it.  The  periods  of  the  sidereal 
year  of  the  earth  will  be  the  same  after  a  thousand  more 
revolutions.  The  mean  form  of  the  orbit  will  never  change. 
It  is  independent  of  the  number  of  worlds,  and  of  the  quantity 
of  matter  that  is  or  has  been  on  either  side  of  it.  What- 
ever be  the  tie  of  the  worlds,  astronomers  should  never  have 
applied  to  fixed  and  periodic  changes  the  word  "  perturba- 
tions." The  word  does  not  belong  to  the  movement  of 
worlds,  so  exactly  balanced  by  Infinite  Wisdom. 

In  what  other  respect  than  as  accounting  for  perturbation 
is  the  theory  of  gravitation  even  remotely  connected  with  the 
movements  of  the  heavenly  bodies  ?  Not  surely  with  their 
motion.  That  gravitation  gives  motion  to  the  planets  has 
never  been  assumed  by  those  who  invented  the  theory,  nor 
by  any  of  the  distinguished  philosophers  who  have  upheld  it. 
All  acknowledge  an  original  impulse  of  motion.  It  is  sup- 
posed that  matter,  when  once  set  in  motion,  tends  to  move 
onwards  in  a  straight  line  with  a  uniform  velocity  forever. 
This  assumption  that  all  motion  is  naturally  in  a  straight 
line,  is,  we  believe,  the  foundation  error;  and  it  is 
this  assumption  which  necessitates  the  supposition  of  an 
attractive  force  to  give  to  the  straight  line  its  unnatural 
curve.  The  assumption  of  this  necessitates  the  suppo- 
sition of  the  centrifugal  force,  to  keep  the  planets  from 
falling  inward  when  drawn  by  the  attractive  force.  Now  it 
is  found  that  the  curvilinear  motion  of  the  planets  can  be 
mathematically  represented  by  the  action  of  these  two  sup- 
posed forces,  —  the  one,  of  gravitation,  which  constantly 
deflects  the  straight  line  into  a  curve,  —  the  other,  of  repul- 
sion, which  prevents  the  planet  from  being  too  much  de- 
flected. From  these,  though  they  may  be  mere  fictions, 

25* 


294          OUTLINES  OF  A  SYSTEM.  OF 

can  be  deduced  mathematically  the  true  motions.  Of 
course,  this  success  of  the  mathematician  does  not  in  the 
least  prove  the  theory. 

Whewell  says,  "  many  men  of  good  intellectual  culture 
entertain  in  relation  to  gravitation  vague  and  perplexed 
ideas,  which  show  very  clearly  that  the  acceptance  of  the 
idea,  is  the  result  of  traditional  prejudice,  not  of  rational 
conviction."  If  the  theory  of  gravitation  be  true,  it  is 
indeed  time  that  every  educated  man  should  have  fixed  and 
definite  ideas  concerning  it.  It  is  not  claimed  for  the  the- 
ory that  this  earth  falls  toward  the  sun  as  a  stone  falls  to  the 
earth.  Attraction  is  equipoised  by  the  repelling  force.  It 
is  a  statical  force  only.  With  the  aid  of  its  opposite  force, 
it  preserves  the  earth's  distance  from  the  sun.  It  is  thus 
supposed  only  to  determine  the  curve  of  the  orbit ;  and  this 
curve  is  modified  somewhat  by  the  attraction  of  other  bodies. 
This  is  the  extent  of  all  that  can  be  claimed  for  gravitation 
as  acting  in  the  solar  system. 

We  have  then  this  simple  intelligible  statement :  the 
impulse  of  the  motion  of  the  planets  which,  not  modified, 
would  produce  motion  in  a  straight  line,  by  the  action  of  the 
centripetal  and  centrifugal  tendencies  results  in  the  curvi- 
linear. The  attractive  force  is  entirely  incompetent  of  itself 
to  give  the  orbit.  It  requires  the  supposition  of  an  opposite 
force  of  equal  intensity.  If  we  should  begin  with  a  belief 
in  the  repulsive  power  of  matter,  this  belief  would  require 
also  the  belief  of  an  opposite  force  of  equal  intensity.  Each 
fiction  requires  another  fiction,  —  the  one  destroying  the 
power  of  the  other.  They  are  useless.  The  planet  with 
them,  or  without  them,  moves  by  its  own  impulse  of  motion. 

If  the  centrifugal  force  is  the  tendency  of  a  planet  to 
assume  a  straight  line  of  motion,  the  strength  of  this  force 


MECHANICAL    PHILOSOPHY.  295 

must  be  determined  by  the  strength  of  the  impulse  of  mo- 
tion. If  the  planet's  force  of  motion  is  always  of  one  degree 
of  intensity,  so  must  be  the  centrifugal  force.  But  a  vary- 
ing attractive  force  requires  a  varying  centrifugal  force. 
The  curve  of  the  orbit  demands  an  equal  balance  of  repul- 
sion and  attraction.  If  the  sun  attract  the  more,  centrifugal 
force  must  repel  the  more,  and  if  by  a  greater  distance  the 
sun  attract  the  less,  centrifugal  force  must  repel  the  less,  to 
preserve  the  curve. 

The  velocity  of  a  planet  is  determined  by  its  distance 
from  the  sun.  Unbalanced  attraction  and  repulsion  cannot 
give  a  determinate  distance,  —  balanced  attraction  and  re- 
pulsion neutralize  each  other  at  any  distance.  We  believe, 
then,  that  we  must  go  at  once  for  the  curve  of  the  orbit,  not 
to  an  original  impulse  of  motion,  but  to  the  intensity  of  the 
force  present  to  the  planet.  It  is  this,  and  this  only,  that 
determines  the  distance,  the  curve  of  the  orbit.  It  is  the 
intensity  of  the  impelling  force  which  governs  the  revolu- 
tion of  the  spheres.  Mathematicians,  for  the  purposes  of 
calculation,  may  refer  to  attractive  and  repulsive  forces, 
may  resort  to  any  fictions  or  hypotheses  which  aid  their 
processes  ;  but  in  philosophy  these  imaginary  lines  can  at 
once  be  discharged.  We  may  look  to  the  heavens  with 
more  simple  and  comprehensible  ideas.  We  may  clear  the 
starry  hosts  from  all  mathematical  intricacies,  and  no  longer 
associate  the  planets  with  radial  and  tangential  forces,  and 
the  complex  fictions  of  human  weakness  ;  we  may  regard  the 
majesty  of  their  movements  as  true  to  the  one  great  law,  — 
velocity  in  proportion  to  orbit,  distance  according  to  the 
impelling  force,  —  the  spheres  as  united  and  oscillating  as  a 
great  whole  by  the  sweep  of  the  bands  of  power,  yet  each 
pursuing  its  own  course  by  its  own  inherent  energy,  cen- 


296  OUTLINES   OF  A   SYSTEM   OF 

turies  upon  centuries  passing  over  them,  yet  in  all  their 
complex  relations  no  permanent  change. 

We  do  not  mean  by  these  remarks  to  undervalue  mathe- 
matical research.  Mathematics  has  its  power  from  its  pecu- 
liar exactness  of  reasoning,  and  the  definite  language  which 
it  employs  in  its  processes.  Mathematical  training  gives  the 
power  of  concentrated  thought ;  but,  as  with  all  other  kinds 
of  reasoning,  its  results,  whether  beneficial  to  the  world  or 
not,  depend  on  the  character  of  the  mind  which  employs  it. 
It  is  not  an  end,  but  an  instrument ;  its  value  consists  not  in 
the  ability  with  wThich  the  instrument  is  used,  but  in  the 
work  accomplished  by  it.  Connected  with  the  physical 
sciences,  it  may  uphold  error  as  well  as  advance  truth.* 

But  there  is  an  error  which  has  done  much  evil  in  the 
world  ;  that  is,  that  it  requires  the  power  of  abstract  mathe- 
matical reasoning  to  understand  mechanical  philosophy.  It 
is  not  so.  The  truth,  if  there  are  truths  only  to  be  arrived 
at  by  the  process  of  mathematical  reasoning,  will  be  fur- 
nished by  the  mathematician.  His  results,  if  valuable,  can 
be  translated  into  the  popular  language.  Mathematical 
investigation  is  a  process,  not  a  result,  —  an  aid,  but  not 
success.  Ferguson,  who  was  surely  distinguished  by  his 

*  Stewart,  in  his  Philosophy,  deprecates  "  that  unqualified  application  of 
the  mathematical  method  to  physics,  which  has  heen  fashionable  for  many 
years,  and  which  seems  to  have  originated  chiefly  in  the  commanding  influ- 
ence which  the  genius  of  Leibnitz  has  so  long  maintained  over  the  scientific 
taste  of  most  European  nations."  He  speaks  "of  the  obvious  tendency 
which  it  has  to  withdraw  the  attention  from  that  unity  of  design  which  it 
is  the  noblest  employment  of  philosophy  to  illustrate."  .  .  .  ';  The  conse- 
quence has  been,  (in  too  many  physical  systems,)  to  level  the  study  of 
nature  in  point  of  moral  interest  with  the  investigations  of  the  algebraist,  — 
an  effect  which  has  taken  place  most  remarkably,  when,  from  the  sublimity 
of  the  subject,  it  was  least  to  be  expected,  in  the  application  of  the  mecha- 
nical philosophy  to  the  phenomena  of  the  heavens." 


MECHANICAL   PHILOSOPHY.  297 

astronomical  knowledge,  hardly  knew  the  notation  of  alge- 
bra, and  could  not  demonstrate  a  proposition  of  Euclid  ;  and 
Kepler,  whose  name  is  indelibly  impressed  on  the  planetary 
system,  was  not  even  a  good  arithmetical  calculator.  Phi- 
losophy is  not  thus  fenced  out  from  men  of  ordinary  educa- 
tion and  common  sense.  The  truths  to  be  understood  are 
few  and  simple  ;  and  it  would  be  of  great  service  if  the 
general  principles  of  philosophy  were  examined  by  those 
who  have  no  educational  bias  to  any  of  the  present  theories  ; 
the  whole,  after  all,  is  but  an  appeal  to  the  common  sense 
of  those  who  are  sufficiently  educated  to  understand  the 
subject. 

It  is  admitted  that  gravitation  cannot  account  for  the 
form  and  orbits  of  comets  ;  and,  if  not  for  these,  then  it 
cannot  for  the  minor  eccentricities  of  the  planets.  The 
difference  is  in  degree  only,  not  in  character.  Sir  John 
Herschell,  in  speaking  of  a  comet,  says  that  the  laws  of  gra- 
vitation are  insufficient  to  account  for  such  a  form  of  equi- 
librium, and  that  such  a  form  is  inconceivable  without  the 
admission  of  repulsive,  as  well  as  of  attractive  forces.  "  But 
if  we  admit  the  matter  of  the  tail  to  be  repelled  from  the 
sun,  and  attracted  by  the  nucleus,  it  no  longer  presents  any 
difficulty."  He  hazards  the  opinion,  in  order  to  obtain  a 
repulsive  power,  that  "  the  sun  is  permanently  charged 
with  electricity."  Arago  found  that  the  attractive  force,  as 
exercised  on  heavy  bodies,  is  inadequate  to  explain  some 
peculiar  motions  of  comets  ;  and  is  of  opinion  that  these 
motions  "  indicate  a  polar  force  which  turns  one  semi- 
diameter  towards  the  sun,  and  strives  to  turn  the  opposite 
side  away  from  that  luminary."  To  aid  the  theory  of  gravi- 
tation in  its  application  to  comets,  the  supposition  of  a  retard- 
ing medium  has  also  been  advanced,  but  with  little  success. 


298  OUTLINES   OF   A   SYSTEM   OF 

The  difficulty,  as  we  have  said,  is  not  in  the  character  of  the 
motions  of  these  bodies  ;  but  the  great  degree  of  the  eccen- 
tricity of  their  orbits,  shows  plainly  a  defect  in  the  theory 
of  gravitation,  which  escapes  notice  when  eccentricity  bears 
but  a  small  proportion  to  the  diameter  of  the  body  or  to  its 
orbit  of  revolution.  It  is  impossible  not  to  perceive  that 
the  sun  has  not  an  attractive  power,  when  we  trace  the  mo- 
tion of  a  comet.  We  will  suppose  a  comet,  millions  of  millions 
of  miles  away  from  the  sun,  moving  from  him  under  the 
impulse  of  its  impelling  force,  until  the  central  attraction, 
when  immeasurably  weakened  by  distance,  changes  the 
direction  of  the  wanderer  and  recalls  it  toward  the  centre ; 
it  returns  rushing  toward  the  sun,  almost  in  a  straight  line, 
and  when  so  near  that  another  quarter  of  an  hour  would 
bring  it  into  contact  with  the  central  luminary,  at  this  near 
point,  although  attracted  to  the  centre  with  a  force  almost 
as  great  as  that  with  which  the  sun  binds  together  the  parts 
of  his  own  mass,  it  again  speeds  away  against  the  full  force 
of  the  sun's  attraction. 

Nor  can  the  sun  give  form  to  the  orbits  of  the  planets  ; 
for  he  cannot,  with  a  force  invariable  on  the  same  mass  and 
at  the  same  distance,  determine  the  form  of  the  ellipses,  or 
the  degree  of  the  eccentricity.  Attraction  does  not  shape 
the  orbit.  We  are  somewhat  acquainted  with  the  mathe- 
matical reasoning  by  which  the  unvarying  central  force  is 
supposed  to  give  the  modifications.  But,  after  all,  an  equal 
central  force  acting  on  any  heavenly  body  at  any  one  dis- 
tance, cannot  do  aught  but  maintain  that  distance  against 
the  uniform  centrifugal  force,  which  is  measured  by  the 
intensity  of  the  impulse  of  motion.  If  there  are  changes  of 
velocity  and  changes  of  curve,  they  must  come  from  a 
change  in  the  force  which  determines  the  motion.  There 


MECHANICAL    PHILOSOPHY.  299 

is  something  belonging  to  the  planet,  not  to  the  sun,  —  a 
change  at  the  circumference,  not  at  the  centre  of  revolu- 
tion, which  gives  the  peculiarities  of  the  orbit.  The  differ- 
ence between  the  orbits  of  Mercury  and  Venus,  for  instance, 
comes  not  from  solar  influence  ;  this  influence  varies  only 
with  the  mass  and  the  distance.  It  is  not  mass  or  distance 
that  determines  eccentricity.  Therefore,  that  which  gives 
a  different  character  to  the  orbits  of  these  two  planets  is 
local,  and  peculiar  to  each.  The  eccentricity  of  the  orbit 
does  not  come  from  central  attraction,  nor  does  its  elliptical 
form ;  nor  consequently,  does  the  mean  distance,  nor  the 
curve,  nor  indeed  any  peculiarity  of  the  orbit  of  any  planet. 

To  our  mind  it  is  another  disproof  of  the  theory  of  gravi- 
tation as  applied  to  the  heavenly  bodies,  that  it  throws 
over  the  solar  system  a  complicated  irregularity.  It  takes 
away  symmetry,  the  simple  and  orderly  relation  of  the 
spheres  ;  by  the  arrangement  of  masses  to  suit  the  theory  it 
destroys  the  idea  of  regular  progression.  For  instance,  the 
theory  presents  the  moon  as  a  mass  of  vapor  compared  with 
its  primary,  while  one  of  Jupiter's  satellites  is  made  more 
dense  than  Jupiter  himself.  One  planet  is  puffed  up, 
another  unnaturally  hardened,  and  relative  density  skips 
back  and  forth  without  method  or  order.  Uranus  is  less 
dense  than  Saturn  ;  Venus  and  Mars  less  dense  than  the 
Earth,  which  lies  between  them.  As  it  has  been  most  sin- 
gularly expressed,  some  are  as  light  as  vapor,  and  some 
heavy  as  lead ;  and  between  the  extremes  are  those  of  the 
consistency  "  of  water,  of  honey,  of  antimony,  and  of  pine 
wood,"  all  confusedly  intermingled  for  the  purpose  of 
adapting  the  heavens  to  the  theory  of  gravitation. 

To  show  that  we  do  not  exaggerate  in  these  statements, 
we  will  quote  from  a  standard  authority.  "  The  planetary 


300  OUTLINES   OF  A   SYSTEM   OF 

system  in  its  relations  of  diameter  and  relative  position,  in 
density,  time  of  revolution,  and  eccentricity  of  orbit,  does 
not  offer  to  our  apprehension,  any  stronger  evidence  of 
natural  necessity  than  the  proportion  observed  in  the  distri- 
bution of  land  and  water  on  the  earth,  and  the  height  of 
mountain  chains.  In  these  respects  we  can  discover  no 
common  law  in  the  regions  of  space,  or  in  the  irregularities 
of  the  earth's  crust."  And  the  heavenly  bodies  are  pre- 
sented "  as  facts  arising  from  the  conflict  of  forces  acting 
under  unknown  conditions."  We  cannot  avoid  the  belief, 
that  no  theory  can  be  sound  which  does  not  unfold  the 
beautiful  symmetry  and  perfection  of  the  universe. 

It  has  been  found  that  the  diameter  of  the  earth  multi- 
plied by  one  hundred  and  ten,  gives  the  sun's  diameter,  and 
that  this  product,  the  sun's  diameter,  multiplied  by  one  hun- 
dred and  ten,  gives  the  distance  of  the  sun  from  the  earth  ; 
and  also  that  the  moon's  diameter  multiplied  by  one  hundred 
and  ten,  gives  her  distance  from  the  earth : 

7920  X  110  =  871,200,  observed  diameter  880,000 
871,200  x  HO  =  95,832,000,  "  distance  95,000,000 

2160x110  =  237,600,        «  «  237,400 

It  appears  from  this,  that  the  diameters  of  the  heavenly 
bodies  have  not  only  a  fixed  proportion  to  each  other,  but 
also  to  their  distances  one  from  the  other.  Diameters  there- 
fore are  not,  if  we  may  be  allowed  the  expression,  deceptive  ; 
they  have  an  honest  value.  It  is  the  circumference  of  the 
planet  and  the  sweep  of  its  orbit,  that  determines  its  relation 
to  others.  Magnitudes  as  presented  to  the  astronomer  are 
more  reliable  than  speculations  as  to  density.  The  one, 
accurate  instruments  and  close  observation  will  give  with 
great  exactness ;  the  other,  however  acute  may  be  the 
mathematician,  however  sound  his  system  of  calculation, 
may  be  altogether  erroneous. 


MECHANICAL  PHILOSOPHY.  301 

We  do  not  believe  that  it  was  by  the  "  conflict  of  mani- 
fold forces,"  that  a  one-hundred-and-tenth  part  of  the  sun 
was  torn  off,  and  carried  one  hundred  and  ten  times  his 
diameter  in  distance,  there  to  be  consolidated  and  shaped 
under  the  direction  of  the  centripetal  and  centrifugal  forces  ; 
and  that  the  accompanying  vapors  were  rolled  off  so  as  to- 
form  a  moon  exactly  one  hundred  and  ten  times  its  diameter 
in  distance  from  the  earth.  We  believe  that  the  diameters 
of  the  heavenly  bodies  are  measured  one  by  the  other,  and 
bear  to  one  other  a  fixed  proportion  ;  that  the  same  meas- 
ure was  used,  and  was  guided  by  the  same  hand  all  over 
the  system  of  worlds  ;  that  all  apparent  disorder  or  irregu- 
larity is  the  distortion  of  facts  as  seen  through  the  mists  of 
our  ignorance. 

We  will  assume  for  Mercury  a  diameter  of  three  thousand 
six  hundred  miles,  and  compare  this  with  the  diameters  of 
Venus,  Earth,  the  Moon,  and  Mars.  If  we  discover  a  fixed 
relation  in  their  magnitudes,  we  may  reasonably  suppose 
that  the  chain  of  progression  extends  through  the  wnole 
system,  even  if  some  of  its  connecting  links  are  hidden. 

Mercury, 3,600  observed  diam.    3,240 

Venus,      .     .     .     3,600  +  3,600     =     7,200  "             "         7,700 

Earth  and  Moon,  7,200  +  7,200     =  14,400  assumed  value,    14,400 

Earth,    ....    7,200  +  720       =     7,920  observed  diam.     7,920 

Moon,    ....     720  +  720  +  720  =  2,160  "          "           2,160 

Mars,  ....    2,160  +  2,160     =     4,320  "          "            4,180 

39,600  miles  39,600 

The  aggregate  of  our  assumed  diameters,  as  thus  "  double 
one  against  the  other,"  is  the  aggregate  of  the  observed 
diameters  ;  and,  while  the  aggregates  thus  agree,  the  diam- 
eters assumed  for  each  do  not  vary  materially  from  the 
magnitudes  given  by  the  astronomer.  If  we  can  show  that 
the  value  of  the  moon  by  increased  rotation  is  6480,  or  in 

26 


302  OUTLINES   OF  A  SYSTEM   OF 

other  words,  that  the  joint  value  of  the  earth  and  moon  is 
14,400  miles,  we  establish  the  fact  that  the  diameters  of 
the  planets  are  "  built  one  upon  the  other."  * 

The  velocity  of  the  earth's  rotation  at  the  equator 
may  be  stated  as  1,037  miles  an  hour.  If  the  diameter 
of  the  earth  were  increased  by  the  diameter  of  the  moon, 
(7,920  +  2,160  =  10,080,)  rotation  in  the  same  time  would 
give  a  velocity  of  about  1,260  miles  an  hour.  The  velocity 
of  the  moon's  rotation  is  2,300  miles  an  hour.  This  is 
made  up  of  the  increase  of  230  miles,  which  would  ensue 
were  she  a  component  part  of  the  earth,  and  of  twice  the 
earth's  velocity,  constituting  the  2,070  miles.  Thus,  her  ro- 
tation at  the  circumference  of  the  local  system  is  three  times 
the  value  of  the  rotation  of  the  earth  at  the  equatorial  regions. 

Earth,    v>  ^:  .     .-    7,920 

Moon,     2160x3  =  6,480 

14,400  miles. 

By  the  multiplication  of  14,400  by  16,  we  have  230,400 
miles,  the  minor  axis  of  the  moon's  orbit ;  by  the  multipli- 
cation of  14,400  by  17,  we  have  244,800,  the  major  axis. 
The  eccentricity  of  the  ellipse  of  the  orbit  is  stated  at  TJT . 
The  mean  of  the  two  extremes  237,600  is  exactly  the  mean 
distance  of  the  moon  from  the  earth  as  deduced  by  obser- 
vation, and  is  the  distance  as  obtained  by  the  multiplication 
of  the  moon's  diameter  by  110. 

The  distance  of  Jupiter  is  5£  times  the  distance  of  the 
earth  from  the  sun.  14,400  X  5£  =  79,200,  which  is  the 
small  diameter  of  Jupiter.  If  we  multiply  the  moon's 
diameter  by  5^,  we  have  11,880,  which  is  about  the  aggre- 

*  These  "  numerical  coincidences "  extend  through  the  whole  system. 


MECHANICAL    PHILOSOPHY.  303 

gate  of  the  observed  diameters  of  Jupiter's  satellites, 
namely,  —  2508  +  2668  +  3377  +  2890  =  11,443  miles. 

The  mean  distance  of  Mercury  from  the  Sun  is  thirty- 
eight  millions  of  miles,  or  forty-five  times  the  Sun's  diameter. 
Deduct  one  diameter,  and  44  X  2  =  88  gives  the  revolution 
of  Mercury  in  days.  The  moon  is  16^-  times  14,400  miles 
from  the  earth  ;  15J-  X  2  =  31  days  rotation.  Is  this  a 
mere  numerical  coincidence  ?  * 

The  sidereal  revolution  of  the  moon  is,  say  twenty-seven 
days ;  the  sun's  rotation,  as  increased  in  relation  to  the 
earth  by  the  earth's  motion  in  the  same  direction,  is  twenty- 
seven  days.  In  movements  thus  involved  and  combined,  the 
sun  and  moon  rotate  the  same  number  of  times  for  every 
revolution  of  the  earth.  Are  the  form  of  the  orbit,  the  cir- 
cumference of  the  planet,  and  its  motion,  determined  by  its 
mass  and  distance  according  to  the  theory  of  'gravitation  ? 
We  rest  in  the  belief  of  a  perfect  symmetry  of  all  the  parts 
of  the  solar  system,  and  a  close  sympathy  of  motion  consti- 
tuting the  universe  a  perfect  whole. 

The  preceding  are  rough  calculations,  selected  from  many 
of  the  same  character,  not  as  the  most  striking,  but  because 
in  a  simple,  unartificial  manner,  they  present  the  fact  ^that 
the  diameters  of  the  spheres,  as  it  were,  grow  out  of  each 
other,  and  that  there  is  a  determinate  relation  of  magnitude 
and  distance  running  through  the  system  of  worlds.  The 

^Mercury, 45    X  2  =     90  days,  observ.  88  days 

Venus,  .     .     .     .     45    +  22£  =    674  X  3  =   202£  "         "         220     " 
Earth,    .     .     .     .     674  +  224=    90    X  4  =    360     "         "         365     " 
Mars,     .     .     .     .     90    +45    =135    X  5=    675     "         "         685     " 
Vesta,    .     .     .     .135+90    =225    X  6  =  1350     "         "       1350     " 
We  thus  roughly  indicate  a  regular  progression  of  the  times  of  resolu- 
tion, which  can  be  extended  through  the  system  with  striking  numerical 
coincidences. 


304  OUTLINES   OP  A   SYSTEM   OF 

relations  of  these  bodies  to  one  other  seem  to  demand  the 
greater  attention  ;  for,  when  distinctly  traced  out,  all  seem- 
ing incongruities  will  vanish,  and  order  will  be  restored  to 
the  heavens,  or,  in  other  words,  the  mind  in  sympathy  with 
nature  will  discover  the  order  that  ever  has  reigned  and 
ever  will  reign  supreme. 

From  the  sudden  decrease  of  the  diameter  of  Mars  rela- 
tively to  that  of  the  Earth,  analogy  would  lead  us  to  believe 
in  a  satellite  or  satellites  accompanying  Mars.  But  the  tel- 
escope does  not  reveal  the  existence  of  these  attendants. 
What  are  the  relations  of  the  Asteroids  to  Mars  ? 

By  a  hasty  generalization  we  are  disposed  to  end  the  first 
series  of  planets  with  the  Earth,  and  to  consider  Mars  as 
intermediate,  or  pertaining  in  some  degree  at  least  to  the 
system  of  worlds  between  the  Earth  and  Jupiter.  Is  there 
not  another  system  of  Asteroids  between  Saturn  and  Ura- 
nus, and  another  beyond  the  bounds  of  Neptune,  and  does 
not  system  thus  interlace  with  system  through  the  great 
whole  ? 

We  turn  our  attention  for  a  moment  to  the  nebular 
hypothesis,  a  short  time  since  so  generally  believed,  now 
fading  away  under  the  clearer  light  of  modern  science.  It 
has  been  thus  described  :  —  "  The  assemblage  of  stars  that 
form  at  present  our  solar  system,  were  first  confounded  in 
one  celestial  body,  resembling  one  of  those  mysterious 
nebulas  we  see  floating  in  the  celestial  spaces."  .  .  .  .  "  But 
soon  the  development  begins.  A  principle  of  concentra- 
tion,—  gravitation,  —  counterbalances  the  unlimited  expan- 
sion of  the  gaseous  matter,  brings  the  molecules  nearer 
together,  and  groups  them  in  a  spheroidal  mass.  This  ap- 
proximation allows  the  molecules  different  in  nature  to  act 
upon  each  other  according  to  their  chemical  affinities  ;  the 


MECHANICAL    PHILOSOPHY.  305 

process  of  life  commences,  and  its  earliest  manifestation  is 
light  and  heat.  The  nebula  is  detached  from  the  general 
mass,  under  the  form  of  a  luminous  spheroid  traced  in  the 
obscurity  of  the  heavens.  This  is  the  first  step  in  the  pro- 
cess of  formation."  "  This  gaseous  spheroid  then  resolves 
itself  into  local  agglomerations,  which,  while  concentrating 
each  in  itself,  under  the  influence  of  gravitation  and  chemi- 
cal combinations,  separate  from  each  other  in  distinct 
spheres.  Whether  this  phenomenon  is  effected,  as  La  Place 
imagines,  by  the  successive  separation  and  agglomeration  of 
concentric  layers  of  the  solar  atmosphere,  or  in  virtue  of 
some  organic  law  still  unknown,  is  of  little  importance  here. 
The  fact  of  the  separation  of  the  different  bodies  of  our  solar 
system  into  a  number  of  spheres,  planets,  and  satellites,  is 
not  less  certain,  and  constitutes  one  of  the  essential  and 
incontestible  phases  of  its  development." 

From  another  work  we  extract:  —  "The  idea,  then, 
which  I  form  of  the  progress  of  organic  life  upon  the  globe, 
(and  the  hypothesis  is  applicable  to  all  similar  theatres  of 
vital  being,)  is,  that  the  simplest  and  most  primitive  type 
(under  the  law  to  which  that  of  like  production  is  subor- 
dinate) gave  birth  to  the  type  next  above  it,  and  this  again 
produced  the  next  higher,  and  so  on  to  the  very  highest."  .  .  . 
"  It  has  been  seen  that,  in  the  reproduction  of  the  higher 
animals,  the  new  passes  through  stages  in  which  it  is  suc- 
cessively fish-like  and  reptile-like."  We  make  these  quota- 
tions to  give  what  is  called  the  progressive  theory  as  applied, 
not  only  to  world-making,  but  also  to  the  development  of 
animal  life. 

To  all  these  theories  we  may  apply  the  language  of 
Cudworth  ;  we  quote  from  his  Intellectual  System  of  the 
Universe,  first  published  in  1678.  "  Wherefore,  infinite 

26* 


306  OUTLINES   OF  A   SYSTEM   OF 

atoms  of  different  sizes  and  figures,  devoid  of  all  life  and 
sense,  moving  fortuitously  from  eternity  in  infinite  space  ; 
and  making  successively  several  encounters,  and  conse- 
quently various  implexions  and  entanglements  with  one 
another,  produced  first  a  confused  chaos  of  these  omnifarious 
particles,  jumbling  together  with  infinite  variety  of  motions ; 
which  afterward,  by  the  tugging  of  these  different  and  con- 
trary forces,  whereby  they  all  hindered  and  abated  each 
other,  came,  as  it  were,  by  joint  conspiracy,  to  be  conglom- 
erated into  a  vortex  or  vortices  ;  where,  after  many  convo- 
lutions and  evolutions,  molitions  and  essays  (in  which  all 
manner  of  tricks  were  tried,  and  all  forms  imaginable  exper- 
imented,) they  chanced,  in  length  of  time,  here  to  settle 
into  this  form  and  system  of  things,  which  now  is,  of  earth, 
water,  air,  and  fire  ;  sun,  moon,  and  stars  ;  plants,  ani- 
mals, and  men  ;  so  that  senseless  atoms,  fortuitously  moved, 
and  material  chaos,  were  the  first  original  of  all  things." 

There  is  another  theory  somewhat  more  recently  revived. 
It  is  the  opposite  of  the  development  hypothesis,  whether 
applied  to  world-making,  or  to  the  production  of  the  higher 
orders  and  types  of  animal  life  from  the  lower.  It  is  the 
very  reverse,  —  a  degradation  theory ;  and  shows  us  ani- 
mal life  sinking  below  its  former  level.  The  reptiles,  for- 
sooth, are  not  so  large  as  they  once  were.  There  are 
species  of  fishes  brought  into  existence  with  eyes  misplaced, 
and  mouths  askew.  We  will  again  quote  from  Cud  worth  : 
"  Wherefore,  they  affirm  that  the  earth  brought  forth  divers 
monsters,  and  irregular  shapes  of  animals ; 

"  Orba,  pedum  partim,  manuum  viduata  vicissim, 
Multa  sine  ore  etiara,  sine  vultu,  ca3ca  reperta." 

Of  course,  we  do  not  impute  these  speculations  to  the  the- 


MECHANICAL    PHILOSOPHY.  307 

ory  of  gravitation.  They  are  not  new.  In  the  old  atomic 
philosophy,  long  before  the  theory  of  gravitation  was  an- 
nounced, they  were  presented.  But  it  is  an  objection  to 
this  theory,  that  it  permits  the  belief  of  the  world-making 
and  life-giving  power  of  matter,  as  resuscitated  in  modern 
times,  to  find  a  resting  place  in  the  mind.  If  it  does  not 
produce  the  nebular,  the  progressive,  and  the  degradation 
hypotheses,  it  does  not  place  itself  as  a  barrier  against 
their  introduction.  This  theory  and  these  speculations  are 
not  in  opposition  to  each  other  ;  and  it  behooves  those  who 
would  maintain  the  doctrine  of  the  attractive  power  of 
matter,  so  to  limit  this  power  that  it  sha41  never  be  repre- 
sented as  the  potential  cause  of  all  things. 


CHAPTER    XII. 


"IF  HIS  SUN  ROLLS  OVER  MY  HEAD  AND  WARMS  ME, — IF  HIS  WIND 
COOLS  AND  REFRESHES  ME,  —  IF  HIS  VOICE  SPEAKS  TO  ME,  WHETHER 
IN  THE  THUNDER  AT  MIDNIGHT,  OR  IN  THE  WHISPERS  OF  THE 
FOREST,  OR  BUT  IN  THE  RUSTLING  OF  A  LEAF,  —  IF  HIS  SEASONS 
STILL  COME  ROUND  TO  ME  IN  THEIR  GRATEFUL  VICISSITUDE,  — 
AND  WHEREVER  I  LOOK  IN  OUTWARD  NATURE,  I  BEHOLD  CONSTANT 
ACTION,  CHANGE,  AND  JOY,  —  I  DO  NOT  SUPPOSE  THAT  BRUTE  AND 
SENSELESS  MATTER  CAUSES  ALL  THIS  BY  ITS  INHERENT  POWER, 
WHETHER  ORIGINAL  OR  DERIVED,  —  BUT  THAT  THE  SPIRIT,  THE 
PERSON  WITHIN,  CONTROLS,  VIVIFIES,  AND  PRODUCES  ALL." 

Francis  Bowen. 

IT  may  be  said  that  if  our  assertion,  that  the  earth  is  sub- 
ject to  occasional  and  periodic  oscillations  of  surface,  were 
correct,  these  oscillations  would  be  indicated  by  cracks  and 
fissures  ;  that  as  earthquakes  show  their  agitations,  so  would 
these  fluctuations  declare  themselves  by  inequalities  of  sur- 
face. But  this  would  not  follow  ;  for  earthquakes  are  lim- 
ited, abrupt  disturbances,  while  the  more  gentle  undulations 
of  the  earth,  which  we  suppose,  would  be  analogous  in  their 
movements  to  the  bending  of  an  elastic  spring,  the  curve  of 
which  is  too  gradual  and  too  extended  to  produce  any  rup- 
ture in  its  parts.  Elevation  of  the  earth's  surface  would 
gradually  fade  away  into  depression  without  any  break  or 
abrupt  change  to  mark  its  bounds. 

The  Britannia  tubular  iron  bridge,  it  is  said,  at  times 
contracts  and  expands  to  the  extent  of  three  inches.  This 


MECHANICAL  PHILOSOPHY.  309 

is  a  much  greater  change  of  atomic  structure  in  proportion 
to  the  length  of  the  bridge,  than  the  change  in  the  structure 
of  the  earth  necessary  to  produce  the  rise  and  fall  indicated 
by  the  barometer.  "  The  action  of  the  sun  at  mid-day  does 
not  move  the  tubes  of  the  bridge  more  than  a  quarter  or 
three  eighths  of  an  inch.  The  daily  expansion  and  con- 
traction of  the  tubes  varies  from  half  an  inch  to  three  inches, 
attaining  either  the  maximum  or  minimum  about  3  o'clock, 
A.  M.  and  P.  M."  This  statement  is  copied  from  a  London 
paper  ;  if  correct,  it  is  in  some  degree  a  confirmation  of  our 
views. 

Unquestionably  there  are  many  plausible  objections  that 
can  be  urged  against  the  hypothesis  which  we  have  offered. 
It  is  of  course  incomplete  ;  there  is  much  to  be  learned ; 
much  remains  for  examination,  much  for  further  explanation. 
We  but  indicate  the  mine,  presenting  only  specimens  of  the 
surface-ore,  not  the  raised  and  refined  metal.  The  laws  of 
force  require  assiduous  attention  for  their  development,  as 
the  currents  of  its  transfer  must  necessarily  be  numerous 
and  complicated. 

Our  system  has  not  the  simplicity  of  the  theory  that  all 
matter  attracts  according  to  one  unvarying  law,  nor  is  it  so 
readily  and  easily  applied.  And  for  this  very  reason  we 
believe  that  our  explanation  is  more  true  to  nature  ;  for, 
while  it  throws  a  clear  light  over  some  prominent  phenome- 
na, it  has  not  the  vagueness  which  would  permit  its  applica- 
tion at  once  to  every  fact.  On  the  other  hand,  a  theory  may 
cover  a  vast  ground  from  its  very  vagueness  and  indefinite- 
ness.  A  loose  and  unshaped  robe  can  be  thrown  over  any 
form  ;  but  this  easy  adaptation  does  not  prove  that  it  is  a 
fitting,  useful  garment.  A  theory  is  not  proved  to  be  true 
by  the  readiness  of  its  application.  The  truth  on  the  other 


310  OUTLINES   OF  A   SYSTEM   OF 

hand,  because  of  its  exactness,  shows  its  adaptation  only 
where  the  fact  to  which  it  is  applied  is  well  understood,  and 
its  application  can  be  extended  just  in  proportion  as  the 
relations  of  things  one  to  another  are  distinctly  traced  out. 
A  true  theory  will  be  a  theory  of  progress.  Its  reception 
will  be  marked  by  a  constant  advance  in  knowledge. 

Suppose  it  were  asserted  that  all  matter  was  originally 
created  in  one  dense  and  compact  mass,  and  that  then  a 
repulsive  power  was  given  to  it,  increasing  in  intensity  in 
direct  proportion  to  distance  and  in  inverse  proportion  to 
mass  ;  or  that  space  has  no  fixed  and  definite  extension,  but 
that  it  contracts  and  expands  with  an  intensity  in  propor- 
tion to  the  mass  and  distance  of  the  bodies  which  it  sepa- 
rates. All  facts  could  be  at  once  arranged  under  these 
absurd  hypotheses.  They  merely  assert  that  things  are 
placed  as  they  are  placed.  Does  the  more  reasonable  the- 
ory of  gravitation  give  any  brighter  light  ?  Is  it  not  char- 
acterized by  the  same  vagueness,  and  the  same  readiness  of 
application  to  all  the  phenomena  of  the  universe  ? 

In  former  times  chemistry  divided  all  matter  into  four 
elements,  earth,  air,  fire,  and  water.  This  is  a  simple  clas- 
sification, intelligible  and  applicable  at  once.  Had  it  been 
retained,  however,  the  science  could  have  made  no  possible 
advance.  It  therefore  soon  abandoned  this  easy  generaliza- 
tion. In  its  progress  it  has  divided  and  subdivided,  and  it 
now  presents  us  some  sixty  elements,  and  these  combined 
and  separated  by  the  conflict  of  manifold  forces.  But  it 
will  not  remain  a  confused  collection  of  facts.  It  will  be 
reconstructed  on  a  sure  foundation.  It  will  by  its  minute 
exactness  advance  to  general  principles,  and  while  it  de- 
velops the  relations  of  atoms,  and  of  the  constituent  ele- 
ments of  masses,  it  will  discern  the  unity  of  force,  and 


MECHANICAL    PHILOSOPHY.  311 

discover  the  general  dynamic  laws  which  have  remained 
hidden  because  philosophy  has  supposed  that  already,  in  the 
law  of  attraction,  it  has  attained  its  ultimate  knowledge  of 
the  properties  of  matter. 

There  is  some  reason,  therefore,  to  question  a  theory 
of  too  ready  application,  which  does  as  much  for  the  ad- 
vance of  science  at  first,  at  its  very  inception,  as  after  the 
lapse  of  years.  A  theory  may  be  apparently  useful  in  col- 
lecting all  minor  doubts  into  one  general  doubt,  —  in  remov- 
ing obstacles  from  the  by-paths  of  science,  while  it  gathers 
together  all  those  obstacles  and  forms  a  barrier  in  the  high- 
way of  progress.  The  leading  fact,  on  which  the  law  of  gra- 
vitation is  founded,  is  the  fall  of  bodies  to  the  earth.  To 
this  fact  it  owes  its  origin.  Of  course,  if  it  can  explain 
aught  with  exactness,  if  it  can  give  clear  ideas  in  relation 
to  any  phenomena, — if  it  have  strength,  perspicuity,  dis- 
tinctness of  illustration,  unquestionable  adaptation,  here  it 
will  be  found.  And  if  in  its  application  to  a  falling  stone 
the  mind  receives  no  clear  light,  if  even  this  fact  remains 
enveloped  in  a  mist  of  obscurity,  surely  there  is  some  reason 
to  question  the  value  of  the  theory  in  its  more  remote  and 
extended  applications.  We  will  now  examine  the  theory  of 
attraction  as  explanatory  of  the  fall  of  bodies  to  the  earth. 

It  is  said  that  falling  bodies  move  faster  and  faster  the 
longer  they  continue  in  motion.  To  explain  this  accelerated 
velocity,  we  are  told  that  "  the  force  of  gravitation  acts  not 
at  once,  but  at  every  period  of  descent ;  of  course  the  velo- 
city increases  as  the  time  increases  ;  hence  the  space  de- 
scribed must  be  as  the  time  multiplied  by  the  velocity, 
which  is  the  same  thing  as  to  say  that  the  space  described 
is  as  the  square  of  the  time,  or  the  time  multiplied  by  itself." 

Now  is  it  invariably  true  that  falling  bodies  move  faster 


312  OUTLINES   OF  A   SYSTEM   OF 

and  faster  the  longer  they  continue  in  motion  ?  Does  the 
force  of  gravitation  act,  not  at  once,  but  at  every  period  of 
the  descent  ?  The  answer  must  be  that  this  is  not  rigorously 
true  in  relation  to  bodies  falling  in  an  arc,  as  in  the  case  of 
a  pendulum,  nor  in  the  case  of  water  in  downward  motion 
over  an  inclined  plane.  The  space  described  by  a  falling 
body  is  as  the  square  of  the  time,  only  when  the  fall  is 
perpendicular. 

It  is  the  change  of  the  level  of  rotation  which  gives  the 
uniformly  accelerated  motion.  The  velocity  has  no  relation 
to  the  time  of  the  fall,  nor  to  the  space  described  by  the 
motion.  It  is  measured  by  the  degree  of  the  change  in  the 
orbit  of  rotation.  This  is  the  only  statement  rigorously 
true,  and  universally  applicable  to  all  the  circumstances  of 
a  falling  body.  If  we  divide  the  space  of  the  perpendicular 
fall  into  equal  parts,  the  velocity  of  the  first  part  will  be  as 
one,  of  the  second  as  three,  of  the  third  as  five,  and  so  on  ; 
for  the  force  of  any  part  of  the  descent  will  be  its  own  spare 
force  of  descent,  with  the  addition  of  the  force  of  the  pre- 
ceding parts.  The  same  degree  of  force  always  describes 
the  same  space  in  the  same  time  ;  therefore  in  the  perpen- 
dicular fall  the  product  is  the  same,  whether  the  time  or 
the  space  is  squared. 

The  question  then  is,  whether  the  uniformly  accelerated 
motion  of  a  falling  body  is  the  result  of  the  time  in  which  it 
has  been  moved  by  the  gravitating  power,  or  whether  it  is 
the  result  of  the  change  of  the  level  of  rotation. 

On  our  theory,  the  spare  force  of  rotation  being  deter- 
mined by  the  degree  of  the  change  of  level,  the  downward 
motion  of  the  falling  body  would  have  an  increasing  velocity  ; 
for  the  spare  force  increases  with  every  line  of  actual  descent. 
However  minute  the  division  of  the  space,  the  force  at  every 


MECHANICAL    PHILOSOPHY.  313 

division  and  the  velocity  at  every  division  would  be  doubled. 
Hence  the  reason  for  squaring,  or  multiplying  by  itself,  the 
space  described  by  the  fall.  It  is  just  what  would  be 
affirmed  as  the  result  of  the  theory,  without  recourse  to 
observation,  experiment,  or  admeasurement. 

On  the  other  hand,  a  uniform  acceleration  of  the  motion 
of  a  falling  body  could  never  have  been  supposed  as  a  neces- 
sary result  of  the  attraction  of  the  earth,  and  when  observa- 
tion presents  the  fact,  the  law  of  gravitation  can  give  no 
explanation  or  elucidation  of  it.  According  to  the  theory, 
the  power  of  attraction  varies  only  with  the  mass  and  with 
the  distance.  The  accelerated  motion  is  from  an  increased 
force  without  an  increase  of  the  attracting  mass,  and  a  force 
increased  far  beyond  what  the  lessening  distance  could 
supply. 

Most  unquestionably,  an  increasing  velocity  of  motion 
under  the  same  circumstances  implies  a  greater  producing 
force.  To  obviate  this  difficulty,  it  is  supposed  that  the 
attraction  of  the  earth  is  cumulative,  increments  of  force 
being  added  in  proportion  to  the  time  in  which  the  earth 
attracts.  Why  then  does  not  the  earth's  attraction  accu- 
mulate in  the  body  when  at  rest,  giving  it  more  and  more 
weight  or  tendency  to  descend  ?  Why  does  not  this  attrac- 
tion accumulate  in  water  falling  over  an  inclined  plane  ? 
The  water  is  in  motion  uniformly  and  constantly  towards  the 
earth.  How  does  the  earth,  when  putting  forth  an  increas- 
ing attractive  power,  discriminate  between  bodies  at  rest, 
bodies  moving  obliquely  downwards,  and  those  in  direct 
motion  toward  her  centre  ?  How  does  the  earth  propor- 
tion the  velocity  to  be  added  to  that  already  conferred  ? 
The  theory  of  gravitation  seems  to  require  an  intelligent 
attracting  power,  with  a  nice  perception  of  time,  and  the 
27 


314  OUTLINES   OF  A   SYSTEM   OF 

ability  of  making  mathematical  calculations,  so  that  force 
shall  be  added  in  the  right  degrees,  according  to  the  chang- 
ing circumstances  of  the  moving  body. 

Galileo,  who  first  announced  the  law  of  the  square  of  the 
time,  was  much  perplexed  by  it,  and  ascribes  it,  somewhat 
doubtingly,  to  the  simplicity  of  the  works  of  nature,  saying, 
"If  we  attend  carefully,  we  shall  find  that  no  mode  of 
increase  of  velocity  is  so  simple  as  that  which  adds  equal 
increments  in  equal  times ;  as  the  uniformity  of  motion  is 
defined  by  the  equality  of  spaces  described  in  equal  times, 
so  we  may  conceive  of  the  uniformity  of  motion  to  exist 
where  equal  velocities  are  added  in  equal  times."  Had 
this  train  of  reasoning  been  followed  out,  the  acceleration 
would  have  been  imputed  to  the  change  of  level,  to  the  dis- 
tance of  the  fall,  not  to  the  length  of  the  time  of  the  fall ; 
it  would  have  been  traced  to  the  body  falling,  not  to  the 
earth  on  which  it  falls,  —  to  a  varying  force,  not  to  the  uni- 
form force  of  attraction.  But  this  reasoning  could  not  be 
resorted  to  by  those  who  believe  gravitation  to  be  the  cause 
of  motion ;  therefore  to  this  day  remains  the  singular 
explanation  of  the  uniform  acceleration  of  falling  bodies, 
that,  to  bodies  in  motion  the  earth  adds  constantly  increas- 
ing increments  of  force  to  be  measured  by  the  squares  of  the 
times ;  that  is,  the  power  of  attracting  increases  with  the 
use  of  the  power. 

From  this  it  follows  that  there  are  two  differing  attrac- 
tions, the  attraction  which  gives  weight  and  that  which 
causes  motion,  —  the  one  of  stationary  intensity,  the  other 
increasing  with  the  time  of  its  action.  A  stone  on  the  sum- 
mit of  a  mountain  has  been  attracted  for  ages  without  an 
increase  of  weight ;  when  it  falls  how  rapid  is  the  increase 
of  the  power  which  draws  it  downward  ! 


MECHANICAL    PHILOSOPHY.  315 

How  simple  and  intelligible  is  the  idea  that  the  earth  has 
no  influence  whatever  in  the  fall  of  a  stone,  —  that  she  im- 
parts neither  a  uniform  impulse  nor  constantly  increasing 
impulses,  —  that  the  force  is  always,  invariably,  in  the  body 
which  moves,  —  that  it  is  the  extent  of  the  fall,  not  the  time 
of  the  fall,  which  measures  the  extent  of  the  force  liberated 
from  the  force  of  rotation,  —  that  this  force  according  to  its 
intensity  gives  motion,  not  downward  only,  but  laterally  and 
upward,  —  that,  if  the  space  described  between  the  two 
levels  of  rotation  of  the  descending  body  is  measured,  the 
quantity  of  force  liberated  to  act  in  a  new  direction  is  ascer- 
tained. This  simple  solution  takes  away  all  the  mystery 
which  so  long  has  enveloped  the  subject. 

And  the  converse  act,  the  raising  of  a  stone  to  a  superior 
level  of  rotation,  confirms  this  view.  To  a  stone  at  rest, 
additional  force  for  its  new  relative  position  must  be  applied, 
and,  however  supplied,  its  intensity  is  just  the  force  of  its  fall 
through  the  same  distance  ;  in  fact,  the  force  of  the  fall  is  the 
force  for  the  rise,  as  is  shown  in  the  oscillations  of  a  pendulum. 

But  what  is  gravitation  ?  "A  name,"  said  one  of  our 
strongest  men,  "  that  is  given  to  the  veil  which  covers  the 
unknown  from  our  sight."  Its  original  signification  was 
heaviness.  Transferred  from  the  tendency  to  descend  to 
the  act  of  descent,  from  the  act  of  descent  to  the  "effect  of 
descent,  from  the  effect  of  descent  to  the  principle  by  which 
all  bodies  descend,  thence  it  went  from  the  earth  to  the 
heavens,  first  deflecting  or  bending  the  otherwise  straight 
line  of  the  motion  of  the  moon,  then  curving  the  orbits  of 
all  the  planets,  then  serving  as  the  impelling  power  of  the 
sphere,  then  as  the  cause  of  all  the  perturbations  of  the 
orbits  of  the  planets,  and  of  the  eccentricity  of  the  orbits  of 
the  comets,  then  causing  the  motion  of  the  binary  stars,  one 


316  OUTLINES    OF   A    SYSTEM    OF 

around  the  other,  and  wheeling  the  astral  systems  around  a 
centre  in  the  direction  of  the  Pleiades.  Returning  again 
to  the  earth,  attraction  takes  under  its  ample  folds  every  act 
of  masses,  every  motion  of  atoms,  —  the  first,  last,  and  only 
cord  by  which  philosophy  ties  the  creation  together,  in 
atoms,  masses,  worlds,  and  systems  of  worlds,  aided  perhaps 
somewhat  by  centrifugal  force,  —  the  abhorrence  of  nature 
for  curvilinear  motion ! 

The  gradual  extension  of  the  power  of  gravitation  is  well 
known  by  those  who  pierce 

•-.*  "the  long-neglected,  holy  cave, 

The  haunt  obscure  of  old  Philosophy." 

Long  before  the  days  of  Newton,  the  doctrine  of  the  attrac- 
tion of  the  earth  was  taught  and  generally  believed.  Mag- 
netic attraction  was  the  matrix  of  the  idea.  An  analogy 
was  early  traced  out  between  the  descent  of  falling  bodies 
and  the  rushing  of  particles  of  iron  to  the  magnet.  Thus 
was  established  a  supposed  principle,  —  a  tendency  or  desire 
of  bodies  for  the  presence  of  each  other,  an  idea  which  is 
thus  curiously  expressed  by  Bacon :  — "  The  electrical 
operation,  concerning  which  Gilbert  and  others  since  him 
have  made  up  such  a  wonderful  story,  is  nothing  else  than 
the  appetite  of  a  body  excited  by  friction."  This  appetite 
of  matter  for  matter  was  the  germ  of  the  theory,  which  has 
taken  such  rapid  strides  from  its  inception  by  the  elder 
philosophers  to  the  present  conception  of  the  schools. 

The  great  extension  of  this  appetite  of  the  earth  for  the 
matter  of  adjacent  masses  to  an  appetite  for  the  matter  of 
the  moon,  dates  from  the  time  of  Sir  Isaac  Newton.  Be- 
fore his  time  it  was  hinted  at,  supposed,  timidly  expressed, 
considered  possible.  The  idea  had  never  been  distinctly 


MECHANICAL  PHILOSOPHY.  317 

avowed.  It  was  in  men's  minds  a  "  shadowy  belief.''  Its 
destined  enunciation  was  reserved  for  after-times.  New- 
ton, as  we  shall  see,  disclaimed  the  belief. 

The  first  conception  that  the  attraction  of  the  earth 
extended  to  the  other  spheres  thus  took  its  rise.  When  a 
body  is  falling  to  the  earth,  it  also  partakes  of  the  motion  of 
the  earth  around  its  axis.  Hence  the  idea  that,  some  how 
or  other,  the  fall  to  the  earth  is  connected  with  the  motion 
of  the  earth.  The  fall  of  an  apple  from  the  mast-head  of  a 
ship,  which  partakes  also  of  the  motion  of  the  ship,  and  be- 
tween the  two  forces  describes  a  curve  in  its  fall,  is  one  of 
the  connecting  links  of  the  fabrication  of  the  chain  of  attrac- 
tion,—  both  motions  in  the  same  time,  one  modifying  the 
direction  of  the  other,  —  surely  they  indicate  one  cause  ! 

The  idea  had,  however,  its  refining  process,  its  transition 
state,  before  being  fully  incorporated  into  philosophy.  "  A 
ball  thrown  from  a  cannon  describes  a  curve  by  the  mutual 
action  of  the  impelling  force  and  the  force  of  attraction. 
The  explosion  of  the  gunpowder  would  of  itself  give  the 
rectilinear  line,  the  curve  is  therefore  the  action  of  gravita- 
tion." The  next  step  was,  "  If  the  impelling  force  of  the 
explosion  were  sufficient,  it  would  so  far  overcome  the  force 
of  gravitation,  that  the  ball  would  describe  an  orbit  round 
the  earth,  without  descending  to  its  surface  ;  if  the  impel- 
ling power  were  sufficiently  great,  gravitation  would  act 
only  in  giving  the  cannon  ball  an  orbit  of  rotation  round  the 
earth  like  the  orbit  of  the  moon."  Then  came  the  mathe- 
matical demonstration,  that  an  arc  of  the  deflection  of  the 
moon's  orbit,  cut  off  for  the  calculation,  is  equal  to  the  fall 
of  a  stone  for  an  equivalent  period  of  time.  This  settled  all 
doubts,  and  the  principle  of  gravitation,  going  up  to  the 
moon,  from  this  elevation  could  easily  soar  higher  to  cover 


318  OUTLINES   OF   A   SYSTEM   OP 

all  the  motions  of  the  heavenly  bodies.  There  is  no  hin- 
drance now  to  any  further  extension,  because,  attraction 
being  according  to  the  density,  as  well  as  according  to  the 
distance  of  any  sphere,  philosophy  can  give  to  any  of  the 
heavenly  bodies  just  the  required  power.  Assume  the  law, 
then  most  easily  can  density  be  adjusted,  so  as  to  bring  the 
power  of  the  attraction  of  any  star  to  the  limits  necessary 
for  the  theory.  For  instance,  the  sun  has  too  great  attrac- 
tive power  according  to  bulk  for  the  theory,  but  what  of 
this  ?  Tlis  density  can  be  arranged  so  as  most  exactly  to 
suit  the  theory.  For  this  reason  no  sphere  can  trouble  the 
theory,  and  difficulties  are  met  with  only  in  comets  ;  for  in 
their  case  there  is  too  much  indistinctness,  neither  the  bulk 
nor  the  mass  of  these  bodies  being  known. 

It  is  generally  believed  that  Newton  mathematically  de- 
monstrated that  the  attraction  which  impels  a  falling  stone, 
gives  the  deflection  of  the  orbit  of  the  moon,  —  that  is,  ad- 
mitting that  the  impulse  which  gave  motion  to  the  moon, 
was  at  the  beginning  an  impulse  of  rectilinear  motion,  that 
the  attraction  of  the  earth  gives  the  curvilinear  form,  and 
determines  the  circle  of  her  revolution.  We  copy  an  abstract 
of  the  demonstration  from  the  London  Encyclopedia,  Article, 
Newtonian  Philosophy,  as  in  a  very  few  words  it  conveys 
the  process.  "  If  we  imagine  the  moon  deprived  of  all  her 
motion,  and  be  let  go  so  as  to  descend  toward  the  earth 
with  the  impulse  of  all  that  force  by  which  it  is  retained  in 
her  orbit,  it  will  in  the  space  of  one  minute  of  time  describe 
in  its  fall  15£  Paris  feet ;  for  the  versed  sine  of  that  arc, 
which  the  moon  describes  in  the  space  of  one  minute  by  its 
mean  motion,  at  the  distance  of  sixty  semi-diameters  of  the 
earth,  is  nearly  16TV  Paris  feet.  Wherefore,  since  that 
force  in  approaching  the  earth  increases  in  the  reciprocal 


MECHANICAL  PHILOSOPHY.  319 

duplicate  proportion  of  the  distance,  and  upon  that  account 
at  the  surface  of  the  earth  is  60  X  60  greater  than  at  the 
moon,  a  body  in  our  regions  falling  with  that  force  ought  in 
the  space  of  one  minute  of  time  to  describe  60  x  60  X  15£ 
Paris  feet,  and  in  the  space  of  one  second  of  time  to  describe 
15J  of  those  feet,  and  with  this  very  force  we  actually  find 
that  bodies  here  on  earth  do  actually  descend." 

This  demonstration  is  incomplete  in  many  points  of  view. 
In  the  first  place,  it  is  assumed  that  the  stone  falls  by 
attraction.  In  the  next  place,  the  moon  being  of  one  quar- 
ter of  the  diameter  of  the  earth,  there  is  her  reciprocal 
attraction  to  enter  as  an  element  of  calculation  ;  for  the 
attractive  force  of  the  stone  and  earth  would  not  measure 
the  joint  attractive  force  of  the  earth  and  moon.  Her  mass, 
never  to  be  ascertained,  would  influence  the  result.  Again, 
the  resisting  medium  of  the  motion  of  the  stone  and  the 
moon  may  be  different,  making  the  fall  and  deflection  of 
different  values  for  the  same  time. 

But  admit  that  the  stone  falls  by  attraction,  that  the 
moon's  greater  mass  does  not  vary  the  strength  of  the 
attractive  force,  and  that  the  media  through  which  they 
move  are  the  same,  the  attraction  for  the  stone  is  a  con- 
stantly increasing  force,  giving  constant  and  uniform  accele- 
ration of  motion,  while  the  attraction  for  the  moon  is  a  stati- 
cal force,  bearing  with  uniform  intensity  or  weight.  Attrac- 
tion for  the  falling  stone  is  a  cumulative  energy.  —  for  the 
moon  a  constant  power.  The  moon  is  not  drawn  toward  the 
earth,  but  keeps  the  same  orbit ;  she  preserves,  so  far  as 
relates  to  the  force  of  gravitation,  one  distance.  If  two, 
three,  or  four  similar  arcs  be  cut  off,  of  two,  three,  or  four 
minutes,  the  aggregate  of  deflection  will  be  found  by  the 
simple  addition  of  the  deflection  of  each,  —  the  aggregate 


320  OUTLINES   OF   A   SYSTEM    OF 

of  the  fall  of  the  stone  for  two,  three,  or  four  seconds,  will 
be  found  by  squaring  the  time,  not  by  the  simple  addition 
of  the  time. 

If  we  take  for  one  element  of  calculation  an  uniformly 
accelerated  velocity  to  be  handled  mathematically  in  com- 
parison with  an  equable  velocity,  it  must  be  motion  for  a 
definite  time,  and  the  mean  of  this  varying  velocity  must 
be  deduced  as  its  measure  or  value  ;  for  instance,  take  the 
time  of  the  fall  of  the  stone  equal  to  one  revolution  of  the 
moon,  find  the  mean  velocity,  and  compare  this  mean  velocity 
with  the  velocity  of  the  moon  in  her  orbit.  Will  a  body 
falling  for  the  whole  time  of  the  revolution  of  the  moon, 
have  a  mean  velocity  equal  only  to  the  deflection  of  the 
moon  in  one  orbitual  circle  ?  Even  here  there  will  be  only 
an  approximation  to  a  common  standard  ;  for  the  true  ele- 
ment for  calculation  is  the  mean  velocity  of  the  falling  stone 
for  the  whole  duration  of  time  for  which  the  moon  has  been 
in  motion.  As  the  proposition  has  been  demonstrated,  the 
result  is  true  of  one  given  arc  of  deflection,  compared  with 
one  second  of  the  time  and  the  resulting  velocity  of  the 
falling  stone.  The  moon,  if  she  were  let  go  and  fell  to  the 
earth,  would  unquestionably  obey  the  laws  of  falling  bodies. 
Her  spare  force  of  rotation  would  be  in  the  same  ratio 
according  to  the  change  of  level.  Every  line  of  her  down- 
ward motion  would  increase  her  velocity.  Continuing  in  her 
orbit,  her  motion  is  uniform,  equable,  ever  the  same,  accord- 
ing to  her  distance  from  her  centre  of  rotation  around  the 
earth  or  its  axis.  The  two  motions  have  no  analogy  ;  there 
is  between  them  no  ground  of  comparison  ;  the  one  is 
equable,  the  other  accelerated,  —  the  one  is  fixed,  the  other 
without  bounds,  —  the  one  is  incidental,  the  other  perpetual. 
They  cannot  be  bound  together  in  the  same  mathematical 


MECHANICAL    PHILOSOPHY.  321 

reasoning,  save  under  the  law  of  equal  areas,  and  that  by 
which  decreasing  areas  of  motion  give  out  the  same  force 
that  equal  increasing  areas  of  motion  would  require. 

To  combine  them  demands  that  a  retarding  element  be 
added  to  the  one,  or  an  accelerating  element  to  the  other, 
and  the  degree  or  value  of  this  new  element  cannot  be  math- 
ematically expressed,  since  it  involves  the  conception  of  an 
infinite  series.  It  plunges  us  at  once  into  the  depths  of 
transcendental  mathematics. 

Newton  was  aware  of  the  incompleteness  of  the  demon- 
stration. He  believed  in  a  subtle  ether  which  filled  all 
space,  and  which  gave  to  the  spheres  a  retarded  velocity. 
His  disciples  discarded  the  ether,  and  succeeding  philoso- 
phers adopted  the  bold  and  bare  conception  of  gravitation, 
which  Newton  thus  expressly  disavows  in  his  often  quoted 
letter  to  Dr.  Bentley. 

"  It  is  inconceivable,"  writes  Newton,  "  that  inanimate 
brute  matter  should,  without  the  mediation  of  something 
else  which  is  not  material,  operate  upon  and  affect  other 
matter  without  mutual  contact,  which  it  must  do  if  gravita- 
tion in  the  sense  of  Epicurus  be  essential  and  inherent  in 
it,  and  this  is  the  reason  why  I  desire  that  you  would  not 
ascribe  it  to  me.  It  is  so  great  an  absurdity  that  I  believe 
no  man,  who  has  in  philosophical  matters  a  competent  way 
of  thinking,  can  ever  fall  into  it."  *  So  even  those  may  dis- 

*  On  this  subject,  Stewart  remarks  in  his  Philosophy,  —  "  It  is  impossi- 
ble to  conceive,  in  what  manner  one  body  acts  on  another  at  a  distance, 
through  a  vacuum.  But  I  cannot  admit  that  it  removes  the  difficulty  to 
suppose,  that  the  two  bodies  are  in  actual  contact.  That  one  body  may  be 
the  efficient  cause  of  the  motion  of  another  body  placed  at  a  distance  from 
it,  I  do  by  no  means  assert ;  but  only  that  we  have  a»  good  reason  to 
believe  that  this  may  be  possible,  as  to  believe  that  any  one  natural  event 
is  the  efficient  cause  of  another." 


322  OUTLINES   OF  A   SYSTEM   OF 

card  the  attraction  of  brute  matter  most  who  revere  the 
name  of  Newton,  —  those  who  are 

"passionate  for  ancient  truth 
And  honoring  with  religious  love,  the  great 
Of  elder  times," 

are  not  compelled  to  adhere  to  a  theory,  which  gives  one 
sphere  a  power  over  another  sphere,  at  a  distance  from  it, 
without  the  mediation  of  something  which  is  not  matter 
that  passes  between  them. 

It  is  not  wonderful  that  Newton  repelled  almost  indig- 
nantly the  imputation  that  he  believed  in  the  attraction  of 
brute  matter ;  but  it  is  surprising  that  any  man  should  have 
a  distinct  conception  of  the  harmony  of  the  spheres,  of  their 
equable  unchanging  velocities,  of  the  fixed  law  of  their 
movements,  and  find  in  their  uniformity  an  analogy  with  a 
falling  stone,  between  which  motions  there  can  be  no  rela- 
tion whatever,  no  ratio  of  velocity,  no  common  condition,  — 
the  one  being  permanent,  the  other  incidental ;  the  one,  as 
it  were  the  accident,  the  other  the  law  of  nature  ;  the  one, 
a  flowing  in  a  determined  orbit,  the  other  a  passage  from  one 
orbit  of  rotation  to  another  orbit  of  rotation ;  the  one 
bearing  the  stamp  of  perpetuity,  the  other  being  the  evi- 
dence of  change  ;  the  one  continuous,  the  other  enduring  but 
for  a  time.  Equally  surprising  is  it  that  any  one  can  look 
upward  to  the  revolving  spheres,  in  number  exceeding  the 
sands  of  the  sea-shore,  all,  every  one,  moving  in  curves  ; 
or  look  downwards,  seeing  there  no  straight  lines  of  motion, 
—  the  smallest  'level  of  the  earth  to  the  eye  of  philosophy 
being  a  curve,  —  knowing  that  the  straight  line,  wherever 
drawn,  would  be  a  line  of  collision  and  impingement,  —  and 
yet  affirm,  that  not  one  sphere  for  one  moment  could  be 


MECHANICAL  PHILOSOPHY.  323 

held  to  the  curve,  without  the  conflicting  force  of  gravitation 
to  overcome  the  natural  rectilinear  law  of  motion. 

We  have  thus  passed  hastily  over  a  vast  extent  of  illus- 
tration, and  present  this  rough  outline  to  the  public  eye. 
We  wish  that  it  were  more  worthy  of  the  subject,  more 
faithful  to  the  idea  that  we  have  formed. 

Not  by  way  of  apology,  but  to  give  the  reason  for  it,  we 
will  advert  for  a  moment  to  our  frequent  recurrence  to  the 
religious  bearings  of  science,  and  to  the  Mosaic  account  of 
the  Creation.  The  association  of  this  research  with  the 
Bible,  came  early  with  the  thought  that  in  the  instance  of 
the  rainbow  philosophy  was  but  the  echo  of  the  voice  of 
God,  and  the  connected  passages  were  read  with  an  in- 
creased reverence  and  intense  interest. 

There  is  no  man,  however  skeptical  the  usual  frame  of 
his  mind,  however  careless  and  worldly  the  usual  train  of 
his  thought,  who  does  not  at  times  look  upward  for  support 
and  direction.  Nor,  in  a  scientific  inquiry,  when  baffled  in 
the  attempt  to  comprehend  the  works  of  Nature,  when 
tossed  on  the  changing  wave  of  theory,  can  the  student 
refrain  from  seeking  light,  direction,  authority,  from  above. 
The  mind  is  so  constituted  as  to  look  for  some  revelation 
beyond  what  the  face  of  nature  presents. 

Were  the  Mosaic  account  of  the  beginning  but  the  fresh- 
ness of  philosophy,  the  earnest  expression  of  the  human 
mind,  when  the  earth  in  her  early  morning  was  first  exam- 
ined by  man,  —  were  the  ideas  mere  thoughts  handed  down 
from  the  beginning  of  the  world,  —  mere  traditions  kept 
pure  and  uncontaminated  in  the  Bible,  preserved  from  the 
defilement  of  a  passage  through  the  minds  of  countless  gen- 
erations,—  like  the  pure  waters  of  a  mountain  lake,  clear 
and  sparkling  in  the  light  of  heaven,  because  kept  from  a 


324  OUTLINES    OF   A   SYSTEM   OF 

soiling  channel,  —  in  this  point  of  view,  worthy  is  the  tradi- 
tion, —  how  much  more  worthy  to  him  who  looks  upon  the 
Bible  as  the  word  of  God ! 

In  whatever  point  of  view  it  may  be  considered,  there 
are  strong  expressions,  there  is  a  force  of  words,  a  striking 
language  in  the  first  of  Genesis,  and  if  studied,  not  in  verbal 
criticism,  but  with  a  tone  of  mind  in  sympathy  with  its 
spirit,  there  may  be  found  light  to  show  the  construction  of 
the  world  and  the  nature  of  the  elements  of  which  it  is  com- 
posed ;  and  light  that  will  dissipate  the  mists  of  skepticism 
which  dim  the  beauty  and  glory  of  creation. 

In  conclusion,  we  ask  for  a  few  minutes'  consideration  of 
the  effect  of  mechanical  theories  of  the  universe  on  faith  in 
the  superintending  Providence  of  God.  A  blameless  life 
and  the  most  fervent  piety  have  often  been  associated  with 
manifest  errors  in  philosophy  ;  and  grievous  faults  and  utter 
indifference  to  religion  have  been  accompanied  by  the  most 
eminent  scientific  attainments.  Therefore  a  man's  theories 
should  never  be  deemed  the  test  of  his  religious  character. 
But,  on  the  other  hand,  the  effect  of  philosophical  speculation 
on  the  general  mind,  —  its  tendency  to  aid  in  the  formation 
of  the  Christian  character,  or  to  produce  a  skeptical  spirit, 
is  a  proper  subject  of  investigation. 

There  are  no  atheists  now.  No  man  avows  his  unbelief; 
nor  are  there  any  theories  put  forth  which  do  not  recognize 
the  existence  of  the  Great  First  Cause.  A  purely  mechan- 
ical theory  of  the  construction  of  the  world,  —  the  nebular 
hypothesis  for  instance,  acknowledges  that  God  created  the 
material  from  which  the  worlds  were  constructed,  and  that 
He  gave  to  it  its  law,  or  mode  of  action.  But  this  being 
accomplished,  the  idea  of  God  becomes  an  abstraction ;  it 


MECHANICAL  PHILOSOPHY.  325 

is  no  longer  a  necessary  part  of  the  speculation.  Matter  has 
been  created,  and  it  acts  ;  the  machine  has  been  constructed, 
and  it  continues  in  operation.  There  is  no  need  of  a  super- 
intending Providence.  Mechanism,  the  power  of  matter, 
stands  in  its  place.  The  sparrow  falls  to  the  ground  because 
of  some  material  sequence.  The  earth  is  self-shaped  and 
self-sustained  ;  its  relative  position  and  motion  are  derived 
from  the  action  of  other  spheres  upon  it.  A  circle  is  thus 
described  around  all  material  things,  excluding  God,  yet 
comprehending  within  its  circumference  all  requisite  power 
for  the  self-preservation  and  self-government  of  matter. 
Notwithstanding  the  chilling  influence  of  this  theory,  a  man, 
from  the  original  bias  of  his  mind,  from  early  education,  or 
by  means  of  the  written  and  spoken  word,  may  retain  his 
faith ;  but  it  is  not  a  theory  to  convert  the  skeptical,  con- 
firm the  wavering,  or  deepen  the  conviction  of  any  mind. 
Therefore,  although  science  has  enrolled  among  its  votaries 
the  names  of  many  men  distinguished  for  their  religious 
faith,  it  has  not  been  preeminent  as  it  should  have  been,  for 
producing  and  confirming  the  religious  character. 

We  believe  that  the  ultimate  test  of  the  soundness  of 
theory  in  philosophy  should  be  its  religious  bearing  on  the 
character  ;  and  that  if  any  mechanical  theory  ascribes  to  mat- 
ter power  to  shape  for  itself  its  masses,  or  to  determine  for 
itself  its  position  and  motion,  thereby  enabling  the  mind  to 
regard  creation  without  the  idea  of  a  present  sustaining 
God,  it  is  not  the  true  theory.  True  philosophy  will  do 
more  than  merely  to  permit  or  tolerate  a  belief  in  God ;  it 
will  compel  the  mind  to  trace  all  things  directly  and  imme- 
diately to  Him. 

The  belief  that  the  universe  is  a  vast  machine,  in  regular 
constant  action  because  of  the  inherent  powers  of  matter, 

28 


326  OUTLINES   OF   A   SYSTEM   OF 

arises  from  a  supposed  analogy  between  the  works  of  God 
and  of  man.  They  ought  not  to  be  thus  associated.  The 
means  and  processes  of  the  mechanic  are  not  the  means  and 
processes  of  the  Artificer  of  worlds.  A  steam-engine  is 
constructed  ;  the  desired  result  is  to  control  and  change  the 
direction  of  the  force  of  steam  by  means  of  the  iron  cylin- 
der, of  bolts  and  rods,  of  pipes  and  valves.  The  object  is 
to  modify  the  action  of  existing  force,  and  this  is  accom- 
plished by  using  the  known  properties  of  matter,  —  its  elas- 
ticity and  force  of  cohesion.  The  engine  constructed,  the 
mechanic  stands  aside,  the  spectator  of  its  action.  Thus 
mechanical  philosophy  regards  the  world.  God,  by  means  of 
the  properties  and  laws  of  matter,  has  constructed  a  world, 
and  He  then  becomes  only  a  witness  of  the  action  of  the 
perfect  machine.  But  there  is  no  analogy  whatever  be- 
tween these  processes,  or  their  results.  The  artisan,  by  the 
use  of  mechanical  powers,  by  wheels,  levers,  and  pullies, 
seeks  to  control  existing  force,  —  to  change  established  mo- 
tion. He  works  with  the  full  understanding,  that,  in  rela- 
tion to  him,  there  are  fixed  laws  of  force,  and  definite  pro- 
perties in  matter.  His  command  over  matter  comes  from 
the  sequences  established  by  a  higher  power.  Not  so  with 
God.  Matter  in  relation  to  Him  has  no  assigned  quality, 
no  position  derived  from  its  inherent  powers.  It  is  clay  in 
the  hands  of  the  potter.  Its  only  attribute  is  obedience, 
and  the  form,  position,  motion  given  to  it,  its  only  possible 
property.  Where  it  is  and  what  it  is  are  from  God.  It 
has  no  will  of  its  own,  nor  is  the  Divine  Artificer  constrained 
to  apply  the  law  which  governs  one  form  of  matter  to  limit 
the  force  of  another  form  of  matter.  Hence  to  God  there  is 
no  machinery  whatever.  A  planet  is  in  its  place,  not  by 
any  virtue  or  energy  of  its  own,  nor  by  the  virtue  or  energy 


MECHANICAL    PHILOSOPHY.  327 

of  any  other  sphere.  It  is  whefe  it  is,  and  moves  as  it 
moves,  not  by  a  mechanical  power,  but  by  a  spiritual  agency, 
—  not  by  machinery,  but  by  the  will  of  God.  One  event 
does  not  happen  because  of  another  preceding  event,  but 
both  from  His  will ;  one  thing  is  not  the  cause  of  another, 
but  all  things  are  obedient. 

There  is  no  necessity,  arising  from  inherent  properties  of 
matter,  that  this  earth  should  be  the  pleasant  home  of  man. 
Matter  of  itself  cannot  minister  to  human  wants.  There  is 
no  absolute  necessity  that  there  should  be  the  regulated 
succession  of  phenomena,  by  which  man  traces  out  order  and 
design.  There  is  no  necessarily  existing  connection  between 
material  cause  and  effect.  All  is  from  the  direct  and  imme- 
diate will  of  God.  The  natural  sequences  of  things,  the 
regulated  successions  of  events,  are  but  ministrations  to  hu- 
man weakness.  The  body  has  wants,  and  they  are  provided 
for ;  the  mind  desires  knowledge,  and  the  creation  is  brought 
down  as  it  were  to  the  level  of  its  comprehension.  An 
order  is  stamped  upon  the  mind,  and  to  this  order,  to  this 
low  degree  of  comprehension,  is  the  creation  adapted. 

A  miracle  declares  the  presence  of  God ;  but  the  miracle 
is  only  the  sudden  withdrawal  of  the  veil  which  uniformity 
of  action  spreads  over  the  Supreme  Power.  And  in  one 
point  of  view  even  the  uniformity  of  God's  Providence  is  a 
miracle.  For  this  very  regulated  succession,  and  these 
apparently  predetermined  results,  are  the  manifestation  of 
the  Supreme  Power  as  conformed  to  the  intellectual  wants 
of  the  individual  man.  Every  instance  in  which  man  traces 
the  conformity  of  one  thing  to  another,  every  instance  of  the 
discovery  of  order  in  the  heavens  or  in  the  earth,  is  the 
manifestation  of  the  Divine  attributes,  which  have  so  con- 
structed the  Universe  and  the  soul  of  man,  that  the  order  in 


328  OUTLINES    OF  A   SYSTEM   OF 

the  one  is  the  counterpart  of  the  order  in  the  other.  In  the 
discovery  of  this  order  is  the  glory  of  philosophy  and  its 
reward,  and  herein  is  philosophy  taught  to  bring  all  its  the- 
ories to  this  ultimate  test :  —  Do  they  impress  on  the  mind, 
not  the  idea  that  there  is  power  in  matter,  and  that  the  uni- 
verse is  a  perfectly  constructed  machine,  but  the  great  idea 
of  a  Father  in  Heaven,  wrho  condescends  to  the  weakness 
of  his  children,  giving  them  not  only  day  by  day  their  daily 
bread,  but  furnishing  them,  in  the  evidences  of  design  con- 
tinually displayed  before  them,  the  intellectual  strength 
which  may  lift  their  minds  to  Him  ? 

"  How  exquisitely  the  individual  Mind 
(And  the  progressive  powers  perhaps  no  less 
Of  the  whole  species)  to  the  External  world 
Is  fitted :  —  and  how  exquisitely  too  — 
Theme  this  but  little  heard  of  among  men  — 
The  External  world  is  fitted  to  the  mind ; 
And  the  Creation  (by  no  lower  name 
Can  it  be  called,)  which  they  with  blended  might 
Accomplish  —  this  is  our  high  argument." 

We  firmly  believe  that  in  the  progress  of  time  there  will 
remain  no  mechanical  theories  of  the  construction  or  of  the 
preservation  of  the  universe.  Does  matter  by  delegated 
power,  or  does  God  directly  determine  the  place  and  posi- 
tion of  all  things  ?  One  or  the  other  is  the  case  ;  there  is  no 
divided  sway.  The  universe  is  a  machine  with  a  far-off 
God  ;  or  the  present  God  sustains,  upholds,  moves  every 
part,  and  this,  not  from  a  law  impressed  upon  matter  from 
the  beginning,  but  because  matter  has  no  quality,  attribute, 
or  power  of  its  own.  It  but  obeys  His  present  will. 

We  have  attempted  to  form  some  definite  idea  of 
power,  of  force,  of  something  which  exists  independently 
of  matter,  which  is  not  a  property  of  matter,  and  which 


MECHANICAL  PHILOSOPHY.  329 

matter  can  never  wield  or  direct.  We  ascribe  to  the  ma- 
terial of  creation  no  power  of  self-direction  or  self-control. 
We  believe  in  power,  because  we  are  conscious  of  exercising 
it  in  some  degree  through  the  will,  by  which  we  can  change 
the  position  and  motion  of  things.  We  compare  our  feeble 
strength  with  the  force  of  the  elements,  and  this  with 
the  intensity  of  the  motion  of  the  world,  and  this  again  with 
the  majestic  movements  of  the  extended  system  of  worlds. 
Nor  will  the  mind  pause  here  ;  it  goes  at  once  to  the  omni- 
potence of  God.  The  acknowledgment  that  the  power  which, 
proceeding  from  human  volition,  acts  directly  on  matter, 
is  something  which  is  independent  of  matter,  born  of  the 
will  and  not  generated  by  mechanism,  is  the  first  step  in 
progress.  Comparing  this  in  its  utter  insignificance  with 
the  power  which  moves  the  great  universe,  knowing  as  we 
must  know  that  this  force  can  proceed  only  from  mind,  we 
are  led  upward  till  we  reach  the  Source  of  all  power. 

We  look  upon  the  universe  as  the  creation  of  God,  set 
forth  as  the  symbol  of  His  wisdom,  —  as  His  thoughts  writ- 
ten out  in  matter.  We  are  not  willing  to  assign  to  matter 
that  which  is  not,  and  which  never  can  be  its  property,  or 
to  degrade  the  spiritual  into  a  pantheistic  commingling  with 
the  material.  We  cannot  conceive  of  a  universe  without  the 
idea  of  the  Creator,  nor  of  a  universe  that  can  contain  God, 
or  be  of  sufficient  extent  or  value  to  give  scope  for  the  attri- 
butes of  the  Omnipotent.  We  have  no  sympathy  with  the- 
ories which  present  the  idea  of  a  gradual  induction  of  order 
from  confusion,  of  a  waiting  for  completeness,  of  extended 
time  as  requisite  to  bring  about  the  desired  results.  We 
love  to  think  that  the  worlds  came  perfect  from  the  hands  of 
their  Creator,  and  that  all  their  changes  are  but  from  one 
perfection  to  another  perfection,  without  a  gradual  process, 


330  OUTLINES   OF   A   SYSTEM,   ETC. 

without  an  intermediate  confusion.  We  believe  not  in  a 
time  when  the  world  was  not  clothed  with  perfect  wisdom  as 
its  vesture.  We  hold  that  philosophy  to  be  the  most  true  to 
the  actual  construction  of  things,  which  most  clearly  estab- 
lishes these  ideas  in  the  mind.  We  like  to  discharge  the 
words,  nature,  law,  regular  succession,  and  the  like,  and  to 
ascend  at  once  to  that  which  they  indistinctly  represent,  — 
to  the  idea  of  "  that  pure  and  holy  Mind  that  with  swift 
thoughts  agitates  the  whole  world."  Why  should  we  confine 
ourselves  to  language  which  gives  the  idea  of  intervening 
powers,  and  which  thus  separates  the  Deity  from  His  works  ? 
The  word  nature  is  but  a  substitution,  —  the  word  law  is 
but  the  obscured  representation  of  Omnipresence,  —  order, 
regulated  succession,  mean  Omniscience,  —  adaptation,  har- 
mony, "  the  agreeable  fitness  of  things,"  vaguely  present 
the  idea  of  a  Father  in  Heaven. 


or  THE 
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